Safety power disconnection for power distribution over power conductors to radio communications circuits

ABSTRACT

Safety power disconnection for remote power distribution in power distribution systems is disclosed. The power distribution system includes one or more power distribution circuits each configured to remotely distribute power from a power source over current carrying power conductors to remote units to provide power for remote unit operations. A remote unit is configured to decouple power from the power conductors thereby disconnecting the load of the remote unit from the power distribution system. A current measurement circuit in the power distribution system measures current flowing on the power conductors and provides a current measurement to the controller circuit. The controller circuit is configured to disconnect the power source from the power conductors for safety reasons in response to detecting a current from the power source in excess of a threshold current level indicating a load.

RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication No. 62/883,027, filed Aug. 5, 2019 and entitled “SAFETYPOWER DISCONNECTION FOR POWER DISTRIBUTION OVER POWER CONDUCTORS TORADIO COMMUNICATION CIRCUITS,” the contents of which is incorporatedherein by reference in its entirety.

The present application and the parent application are also related toU.S. patent application Ser. Nos. 16/203,508; 16/203,520; and 16/203,530all entitled “Safety Power Disconnection For Power Distribution OverPower Conductors To Power Consuming Devices,” all filed Nov. 28, 2018,and U.S. patent application Ser. No. 16/576471, filed Sep. 19, 2019, allfiled from PCT Patent Application Serial No. PCT/IL2018/050368, entitled“Safety Power Disconnection For Power Distribution Over Power ConductorsTo Power Consuming Devices,” and filed Mar. 29, 2018. The '368 PCTapplication claims priority to U.S. Provisional Patent Application Ser.No. 62/479,656 entitled “Safety Power Disconnection For PowerDistribution Over Power Conductors To Power Consuming Devices,” andfiled Mar. 31, 2017. All of the above applications are incorporatedherein by reference in their entireties.

BACKGROUND

The disclosure relates generally to distribution of power to one or morepower consuming devices over power wiring, and more particularly toremote distribution of power to distant or remote units in a powerdistribution system, which may include distributed radio communicationscircuits including, but not limited to, those that can be found indistributed communications systems (DCS) such as distributed antennasystems (DAS) for example, for operation of power consuming componentsof the distant remote units.

Wireless customers are increasingly demanding wireless communicationsservices, such as cellular communications services and Wi-Fi services.Thus, small cells, and more recently Wi-Fi services, are being deployedindoors. At the same time, some wireless customers use their wirelesscommunication devices in areas that are poorly serviced by conventionalcellular networks, such as inside certain buildings or areas where thereis little cellular coverage. One response to the intersection of thesetwo concerns has been the use of distributed antenna systems (DASs).DASs include remote antenna units (RAUs) configured to receive andtransmit communications signals to client devices within the antennarange of the RAUs. DASs can be particularly useful when deployed insidebuildings or other indoor environments where the wireless communicationdevices may not otherwise be able to effectively receive radio frequency(RF) signals from a source.

In this regard, FIG. 1 illustrates a wireless distributed communicationssystem (WDCS) 100 that is configured to distribute communicationsservices to remote coverage areas 102(1)-102(N), where ‘N’ is the numberof remote coverage areas. The WDCS 100 in FIG. 1 is provided in the formof a DAS 104. The DAS 104 can be configured to support a variety ofcommunications services that can include cellular communicationsservices, wireless communications services, such as RF identification(RFID) tracking, Wireless Fidelity (Wi-Fi), local area network (LAN),and wireless LAN (WLAN), wireless solutions (Bluetooth, Wi-Fi GlobalPositioning System (GPS) signal-based, and others) for location-basedservices, and combinations thereof, as examples. The remote coverageareas 102(1)-102(N) are created by and centered on RAUs 106(1)-106(N)connected to a central unit 108 (e.g., a head-end controller, a centralunit, or a head-end unit). The central unit 108 may be communicativelycoupled to a source transceiver 110, such as for example, a basetransceiver station (BTS) or a baseband unit (BBU). In this regard, thecentral unit 108 receives downlink communications signals 112D from thesource transceiver 110 to be distributed to the RAUs 106(1)-106(N). Thedownlink communications signals 112D can include data communicationssignals and/or communication signaling signals, as examples. The centralunit 108 is configured with filtering circuits and/or other signalprocessing circuits that are configured to support a specific number ofcommunications services in a particular frequency bandwidth (i.e.,frequency communications bands). The downlink communications signals112D are communicated by the central unit 108 over a communications link114 over their frequency to the RAUs 106(1)-106(N).

With continuing reference to FIG. 1, the RAUs 106(1)-106(N) areconfigured to receive the downlink communications signals 112D from thecentral unit 108 over the communications link 114. The downlinkcommunications signals 112D are configured to be distributed to therespective remote coverage areas 102(1)-102(N) of the RAUs106(1)-106(N). The RAUs 106(1)-106(N) are also configured with filtersand other signal processing circuits that are configured to support allor a subset of the specific communications services (i.e., frequencycommunications bands) supported by the central unit 108. In anon-limiting example, the communications link 114 may be a wiredcommunications link, a wireless communications link, or an opticalfiber-based communications link. Each of the RAUs 106(1)-106(N) mayinclude an RF transmitter/receiver 116(1)-116(N) and a respectiveantenna 118(1)-118(N) operably connected to the RF transmitter/receiver116(1)-116(N) to wirelessly distribute the communications services touser equipment (UE) 120 within the respective remote coverage areas102(1)-102(N). The RAUs 106(1)-106(N) are also configured to receiveuplink communications signals 112U from the UE 120 in the respectiveremote coverage areas 102(1)-102(N) to be distributed to the sourcetransceiver 110.

Because the RAUs 106(1)-106(N) include radio communications circuitcomponents that require power to operate, such as the RFtransmitters/receivers 116(1)-116(N) for example, it is necessary toprovide power to the RAUs 106(1)-106(N). In one example, each RAU106(1)-106(N) may receive power from a local power source. In anotherexample, the RAUs 106(1)-106(N) may be powered remotely from a remotepower source(s). For example, the central unit 108 may include a powersource 122 that is configured to remotely supply power over thecommunications links 114 to the RAUs 106(1)-106(N). For example, thecommunications links 114 may be a cable that includes electricalconductors for carrying current (e.g., direct current (DC)) to the RAUs106(1)-106(N). If the WDCS 100 is an optical fiber-based WDCS in whichthe communications links 114 include optical fibers, the communicationslinks 114 may by a “hybrid” cable that includes optical fibers forcarrying the downlink and uplink communications signals 112D, 112U andseparate electrical conductors for carrying current to the RAUs106(1)-106(N).

Some regulations, such as IEC 60950-21, may limit the amount of directcurrent (DC) that is remote delivered by the power source 122 over thecommunications links 114 to less than the amount needed to power theRAUs 106(1)-106(N) during peak power consumption periods for safetyreasons, such as in the event a human contacts the wire. One solution toremote power distribution limitations is to employ multiple conductorsand split current from the power source 122 over the multipleconductors, such that the current on any one electrical conductor isbelow the regulated limit. Another solution includes delivering remotepower at a higher voltage so that a lower current can be distributed atthe same power level. For example, assume that 300 Watts of power is tobe supplied to a RAU 106(1)-106(N) by the power source 122 through acommunications link 114. If the voltage of the power source 122 is 60Volts (V), the current will be 5 Amperes (A) (i.e., 300 W/60 V).However, if a 400 Volt power source 122 is used, then the currentflowing through the wires will be 0.75 A. However, delivering highvoltage through electrical conductors may be further regulated toprevent an undesired current from flowing through a human in the eventthat a human contacts the electrical conductor. Thus, these safetymeasures may require other protections, such as the use of protectionconduits, which may make installations more difficult and add cost.

The problems of distributing power to radio communications circuits arenot limited to systems like the DAS 104. Other radio circuits thattransmit or distribute communications signals wirelessly to clientdevices (e.g., cellular phones) may require power. One such othercircuit is a radio node such as can be found in a 4G, 5G, or similarnetwork which may be a small cell radio node or the like.

No admission is made that any reference cited herein constitutes priorart. Applicant expressly reserves the right to challenge the accuracyand pertinency of any cited documents.

SUMMARY

Embodiments of the disclosure relate to safety power disconnection forpower distribution over power conductors to radio communicationscircuits. As a non-limiting example, such power distribution may beprovided to a radio circuit that is configured to transmit or distributecommunications signals wirelessly to client devices (e.g., a cellularphone). Such a radio circuit may be found in a network such as a 4G, 5G,or comparable network and may act as a small cell radio node, operatewith a remote radio head, a macro cell (shared or not), or the radiocircuit may be found in a distributed communications system (DCS). Forexample, the DCS may be a wireless DCS, such as a distributed antennasystem (DAS) that is configured to distribute communications signals,including wireless communications signals, from a central unit to aplurality of remote units having radio communications circuits overphysical communications media, to then be distributed from the remoteunits wirelessly to client devices in wireless communications range of aremote unit. In exemplary aspects disclosed herein, the communicationssystem includes one or more power distribution systems each configuredto remotely distribute power from a power source over current carryingelectrical conductors (“power conductors”) to units physically removedfrom the power source to provide power to radio communications circuitsof the units for operation. For example, a power distribution system maybe installed on each floor of a multi-floor building in which thecommunications system is installed to provide power to the unitsinstalled on a given floor. Each power distribution system includes acurrent measurement circuit configured to measure current delivered bythe power source over the power conductors to units. Each unit isconfigured to decouple the power conductors from its power consumingcomponents (e.g., the radio communications circuits), therebydisconnecting the load of the unit from the power distribution system.The current measurement circuit then measures current flowing on thepower conductors and provides a current measurement to a controllercircuit. The controller circuit is configured to disconnect the powersource from the power conductors for safety reasons in response todetection of a load based on detecting a current from the power sourcein excess of a threshold current level. For example, a person contactingthe power conductors will present a load to the power source that willcause a current to flow from the power source over the power conductors.If another load is not contacting the power conductors, no current (oronly a small amount current due to current leakages for example) shouldflow from the power source over the power conductors. The controllercircuit can be configured to wait a period of time, and/or until amanual reset instruction is received, before connecting the power sourcefrom the power conductors and unit coupling its power consumingcomponents to the power conductors to once again allow current to flowfrom the power source to the units serviced by the power distributionsystem.

In this regard, in one exemplary aspect, a power distribution system isdisclosed. The power distribution system comprises one or more powerdistribution circuits. The one or more power distribution circuits eachcomprise a distribution power input configured to receive currentdistributed by a power source. The one or more power distributioncircuits each also comprise a distribution power output configured todistribute the received current over a power conductor coupled to anassigned radio communications circuit of a remote unit among a pluralityof remote units. The one or more power distribution circuits each alsocomprise a distribution switch circuit coupled between the distributionpower input and the distribution power output. The distribution switchcircuit comprises a distribution switch control input configured toreceive a distribution power connection control signal indicating adistribution power connection mode. The distribution switch circuit isconfigured to be closed to couple the distribution power input to thedistribution power output in response to the distribution powerconnection mode indicating a distribution power connect state. Thedistribution switch circuit is further configured to be opened todecouple the distribution power input from the distribution power outputin response to the distribution power connection mode indicating adistribution power disconnect state. The one or more power distributioncircuits each also comprise a current measurement circuit coupled to thedistribution power output and comprising a current measurement output.The current measurement circuit is configured to measure a current atthe distribution power output and generate a current measurement on thecurrent measurement output based on the measured current at thedistribution power output. The power distribution system also comprisesa controller circuit. The controller circuit comprises one or morecurrent measurement inputs communicatively coupled to the one or morecurrent measurement outputs of the one or more current measurementcircuits of the one or more power distribution circuits. The controllercircuit is configured to, for a power distribution circuit among the oneor more power distribution circuits, generate the distribution powerconnection control signal indicating the distribution power connectionmode to the distribution switch control input of the power distributioncircuit indicating the distribution power connect state, determine ifthe measured current on a current measurement input among the one ormore current measurement inputs of the power distribution circuitexceeds a predefined threshold current level when the distributionswitch circuit is closed to couple the distribution power input to thedistribution power output; and in response to the measured current ofthe power distribution circuit exceeding the predefined thresholdcurrent level, communicate the distribution power connection controlsignal indicating the distribution power connection mode to thedistribution switch control input of the power distribution circuitindicating the distribution power disconnect state.

An additional aspect of the disclosure relates to a method ofdisconnecting current from a power source. The method comprisesdecoupling current from a power conductor to a radio communicationscircuit of a remote unit. The method further comprises measuring acurrent received from a power source coupled to the power conductor. Themethod further comprises determining if the measured current exceeds apredefined threshold current level. The method further comprises, inresponse to the measured current exceeding the predefined thresholdcurrent level, communicating a distribution power connection controlsignal comprising a distribution power connection mode indicating adistribution power disconnect state to cause the power conductor to bedecoupled from the power source.

An additional aspect of the disclosure relates to a distributedcommunications system (DCS). The DCS comprises a central unit. Thecentral unit is configured to distribute received one or more downlinkcommunications signals over one or more downlink communications links toone or more remote units. The central unit is also configured todistribute received one or more uplink communications signals from theone or more remote units from one or more uplink communications links toone or more source communications outputs. The DCS also comprises aplurality of remote units. Each remote unit among the plurality ofremote units comprises at least one radio communications circuit. Eachremote unit among the plurality of remote units also comprises a remotepower input coupled to a power conductor carrying current from a powerdistribution circuit. Each remote unit among the plurality of remoteunits also comprises a remote switch control circuit configured togenerate a remote power connection signal indicating a remote powerconnection mode. Each remote unit among the plurality of remote unitsalso comprises a remote switch circuit comprising a remote switch inputconfigured to receive the remote power connection signal. The remoteswitch circuit is configured to be closed to couple to the remote powerinput in response to the remote power connection mode indicating aremote power connect state. The remote switch circuit is furtherconfigured to be opened to decouple from the remote power input inresponse to the remote power connection mode indicating a remote powerdisconnect state. The remote unit is configured to distribute throughthe at least one radio communications circuit, the received one or moredownlink communications signals received from the one or more downlinkcommunications links, to one or more client devices. The remote unit isalso configured to distribute the received one or more uplinkcommunications signals from the one or more client devices to the one ormore uplink communications links. The DCS also comprises a powerdistribution system. The power distribution system comprises one or morepower distribution circuits. Each power distribution circuit of the oneor more power distribution circuits comprises a distribution power inputconfigured to receive current distributed by a power source. Each powerdistribution circuit of the one or more power distribution circuits alsocomprises a distribution power output configured to distribute thereceived current over the power conductor coupled to an assigned remoteunit among the plurality of remote units. Each power distributioncircuit of the one or more power distribution circuits also comprises adistribution switch circuit coupled between the distribution power inputand the distribution power output, the distribution switch circuitcomprising a distribution switch control input configured to receive adistribution power connection control signal indicating a distributionpower connection mode. The distribution switch circuit is configured tobe closed to couple the distribution power input to the distributionpower output in response to the distribution power connection modeindicating a distribution power connect state. The distribution switchcircuit is further configured to be opened to decouple the distributionpower input from the distribution power output in response to thedistribution power connection mode indicating a distribution powerdisconnect state. Each power distribution circuit of the one or morepower distribution circuits also comprises a current measurement circuitcoupled to the distribution power output and comprising a currentmeasurement output. The current measurement circuit configured tomeasure a current at the distribution power output and generate acurrent measurement on the current measurement output based on themeasured current at the distribution power output. The powerdistribution system also comprises a controller circuit. The controllercircuit comprises one or more current measurement inputs communicativelycoupled to the one or more current measurement outputs of the one ormore current measurement circuits of the one or more power distributioncircuits. The controller circuit is configured to, for a powerdistribution circuit among the one or more power distribution circuits:generate the distribution power connection control signal indicating thedistribution power connection mode to the distribution switch controlinput of the power distribution circuit indicating the distributionpower connect state; determine if the measured current on a currentmeasurement input among the one or more current measurement inputs ofthe power distribution circuit exceeds a predefined threshold currentlevel; and in response to the measured current of the power distributioncircuit exceeding the predefined threshold current level, communicatethe distribution power connection control signal comprising thedistribution power connection mode to the distribution switch controlinput of the power distribution circuit indicating the distributionpower disconnect state.

An additional aspect of the disclosure relates to a radio communicationscircuit. The radio communications circuit comprises a remote power inputcoupled to a power conductor carrying current from a power distributioncircuit. The radio communications circuit also comprises a remote switchcontrol circuit configured to generate a remote power connection signalindicating a remote power connection mode. The radio communicationscircuit also comprises a remote switch circuit comprising a remoteswitch input configured to receive the remote power connection signal.The remote switch circuit is configured to be closed to couple to theremote power input in response to the remote power connection modeindicating a remote power connect state. The remote switch circuit isfurther configured to be opened to decouple from the remote power inputin response to the remote power connection mode indicating a remotepower disconnect state. The radio communications circuit also comprisesa transceiver. The transceiver is configured to distribute received oneor more downlink communications signals received from one or moredownlink communications links, to one or more client devices. Thetransceiver is also configured to distribute received one or more uplinkcommunications signals from the one or more client devices to one ormore uplink communications links.

Additional features and advantages will be set forth in the detaileddescription which follows and, in part, will be readily apparent tothose skilled in the art from the description or recognized bypracticing the embodiments as described in the written description andclaims hereof, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are merely exemplary and are intendedto provide an overview or framework to understand the nature andcharacter of the claims.

The accompanying drawings are included to provide a furtherunderstanding of the disclosure, and are incorporated in and constitutea part of this specification. The drawings illustrate one or moreembodiment(s), and together with the description serve to explainprinciples and operation of the various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an exemplary wireless distributedcommunications system (DCS) in the form of a distributed antenna system(DAS);

FIG. 2A is a schematic diagram of an exemplary optical fiber-based DCSin the form of a DAS configured to distribute communications signalsbetween a central unit and a plurality of remote units, and that caninclude one or more power distribution systems configured to distributepower to a plurality of remote units and provide a safety powerdisconnect of the power source to remote units;

FIG. 2B is a partially schematic cut-away diagram of an exemplarybuilding infrastructure in which the DCS in FIG. 2A can be provided;

FIG. 2C is a more detailed schematic diagram of the DCS in FIG. 2B;

FIG. 3A is a schematic diagram of an exemplary mobile telecommunicationsenvironment that includes radio circuits including, but not limited to,an exemplary macrocell radio access network (RAN) and an exemplary smallcell RAN located within an enterprise environment and configured toservice mobile communications between a user mobile communicationsdevice to a mobile network operator (MNO), wherein the user mobilecommunications device is configured to discover neighboring radio accesssystems to be reported to a serving RAN, and that can include one ormore power distribution systems configured to distribute power throughthe various elements including radio circuits while providing a safetypower disconnect of the power source to the radio circuits;

FIGS. 3B and 3C illustrate exemplary details of an evolved packet core(EPC) and Evolved Universal Mobile Telecommunications System (UMTS)Terrestrial Radio Access Network (E-UTRAN) arranged under Long TermEvolution (LTE) for the mobile telecommunications environment in FIG.3A;

FIG. 4 is a schematic diagram illustrating a power distribution systemthat can be included in the DCS in FIGS. 2A-2C or the RAN of FIGS. 3A-3Cas an example, wherein the power distribution system is configured toprovide a safety power disconnect of the power source to a remote unitin response to a measured current from the connected power source whenthe remote unit is decoupled from the power source during a testingphase;

FIG. 5 is a timing diagram illustrating an exemplary timing sequence ofthe controller circuit in the power distribution system in FIG. 4;

FIG. 6 is a flowchart illustrating an exemplary process of thecontroller circuit in the power distribution system in FIG. 4 couplingthe remote unit during a normal operation phase and instructing theremote unit to decouple from the power source during testing phases tothen measure current from the power source during a testing phase;

FIG. 7 is a graph illustrating exemplary safe and unsafe regions of bodycurrent for a given current impulse time;

FIG. 8 is a schematic diagram illustrating the power distributioncircuit in FIG. 4 configured to distribute power from a power source toa plurality of remote units to provide power for operation of the remoteunits, and provide a safety power disconnect of the power source toremote units in response to a measured current from the power source;

FIG. 9 is a schematic diagram illustrating an exemplary powerdistribution system that can be employed as the power distributionsystem in FIG. 8;

FIG. 10 is a schematic diagram illustrating additional exemplary detailof the controller circuit of the power distribution system in FIG. 8;

FIG. 11 is a diagram of another exemplary power distribution system thatcan be provided in the DCS in FIGS. 2A-2C or the RAN of FIGS. 3A-3C,wherein the power distribution system is configured to provide a safetypower disconnect of the power source to a remote unit in response to ameasured differential current from the connected power source when theremote unit is decoupled from the power source during a testing phase;and

FIG. 12 is a schematic diagram of a generalized representation of anexemplary controller that can be included in any component in a DCS orRAN, including, but not limited to, the controller circuits in the powerdistribution systems for coupling a remote unit to a power source duringa normal operation phase and instructing the remote unit to decouplefrom the power source during testing phases to then measure current fromthe power source during a testing phase, wherein an exemplary computersystem is adapted to execute instructions from an exemplarycomputer-readable link.

DETAILED DESCRIPTION

Embodiments of the disclosure relate to safety power disconnection forpower distribution over power conductors to radio communicationscircuits. As a non-limiting example, such power distribution may beprovided to a radio circuit that is configured to transmit or distributecommunications signals wirelessly to client devices (e.g., a cellularphone). Such a radio circuit may be found in a network such as a 4G, 5G,or comparable network and may act as a small cell radio node, operatewith a remote radio head, a macro cell (shared or not), or the radiocircuit may be found in a distributed communications system (DCS). Forexample, the DCS may be a wireless DCS, such as a distributed antennasystem (DAS) that is configured to distribute communications signals,including wireless communications signals, from a central unit to aplurality of remote units having radio communications circuits overphysical communications media, to then be distributed from the remoteunits wirelessly to client devices in wireless communications range of aremote unit. In exemplary aspects disclosed herein, the communicationssystem includes one or more power distribution systems each configuredto remotely distribute power from a power source over current carryingelectrical conductors (“power conductors”) to units physically removedfrom the power source to provide power to radio communications circuitsof the units for operation. For example, a power distribution system maybe installed on each floor of a multi-floor building in which thecommunications system is installed to provide power to the unitsinstalled on a given floor. Each power distribution system includes acurrent measurement circuit configured to measure current delivered bythe power source over the power conductors to units. Each unit isconfigured to decouple the power conductors from its power consumingcomponents (e.g., the radio communications circuits), therebydisconnecting the load of the unit from the power distribution system.The current measurement circuit then measures current flowing on thepower conductors and provides a current measurement to a controllercircuit. The controller circuit is configured to disconnect the powersource from the power conductors for safety reasons in response todetection of a load based on detecting a current from the power sourcein excess of a threshold current level. For example, a person contactingthe power conductors will present a load to the power source that willcause a current to flow from the power source over the power conductors.If another load is not contacting the power conductors, no current (oronly a small amount current due to current leakages for example) shouldflow from the power source over the power conductors. The controllercircuit can be configured to wait a period of time and/or until a manualreset instruction is received, before connecting the power source fromthe power conductors and unit coupling its power consuming components tothe power conductors to once again allow current to flow from the powersource to the units serviced by the power distribution system.

Before discussing exemplary details of a safety power disconnection forpower distribution networks in communications networks, an exemplarypower distribution system that can include remote power distribution isdescribed in FIGS. 2A-3C. A discussion of the safety power disconnectionfeature begins below with reference to FIG. 4.

In this regard, FIG. 2A is a schematic diagram of such an exemplarypower distribution system 250. In this example, the power distributionsystem 250 is provided in the form of a DCS 200, which is a DAS 202 inthis example. Note that the power distribution system 250 is not limitedto a DCS or being provided in a DCS. As described below with referenceto FIGS. 3A-3C, the power distribution circuit of the present disclosuremay be provided for any radio communications circuit that is configuredto transmit or distribute communications signals wirelessly to clientdevices (e.g., a cellular phone). Such a radio circuit may be found in anetwork such as a 4G, 5G, or comparable network and may act as a smallcell radio node, operate with a remote radio head, a macro cell (sharedor not), or the like. However, for the purposes of illustration, a DASand a radio access network (RAN) are described herein in FIGS. 2A-3C.

A DAS is a system that is configured to distribute communicationssignals, including wireless communications signals, from a central unitto a plurality of remote units over physical communications media, tothen be distributed from the remote units wirelessly to client devicesin wireless communications range of a remote unit. The DAS 202 in thisexample is an optical fiber-based DAS that is comprised of three (3)main components. One or more radio interface circuits provided in theform of radio interface modules (RIMs) 204(1)-204(T) are provided in acentral unit 206 to receive and process downlink electricalcommunications signals 208D(1)-208D(S) prior to optical conversion intodownlink optical communications signals. The downlink electricalcommunications signals 208D(1)-208D(S) may be received from a basetransceiver station (BTS) or baseband unit (BBU) as examples. Thedownlink electrical communications signals 208D(1)-208D(S) may be analogsignals or digital signals that can be sampled and processed as digitalinformation. The RIMs 204(1)-204(T) provide both downlink and uplinkinterfaces for signal processing. The notations “1-S” and “1-T” indicatethat any number of the referenced component, 1-S and 1-T, respectively,may be provided.

With continuing reference to FIG. 2A, the central unit 206 is configuredto accept the plurality of RIMs 204(1)-204(T) as modular components thatcan easily be installed and removed or replaced in a chassis. In oneembodiment, the central unit 206 is configured to support up to twelve(12) RIMs 204(1)-204(12). Each RIM 204(1)-204(T) can be designed tosupport a particular type of radio source or range of radio sources(i.e., frequencies) to provide flexibility in configuring the centralunit 206 and the DAS 202 to support the desired radio sources. Forexample, one RIM 204 may be configured to support the PersonalCommunication Services (PCS) radio band. Another RIM 204 may beconfigured to support the 700 MHz radio band. In this example, byinclusion of these RIMs 204, the central unit 206 could be configured tosupport and distribute communications signals, including those for thecommunications services and communications bands described above asexamples.

The RIMs 204(1)-204(T) may be provided in the central unit 206 thatsupport any frequencies desired, including, but not limited to, licensedUS FCC and Industry Canada frequencies (824-849 MHz on uplink and869-894 MHz on downlink), US FCC and Industry Canada frequencies(1850-1915 MHz on uplink and 1930-1995 MHz on downlink), US FCC andIndustry Canada frequencies (1710-1755 MHz on uplink and 2110-2155 MHzon downlink), US FCC frequencies (698-716 MHz and 776-787 MHz on uplinkand 728-746 MHz on downlink), EU R & TTE frequencies (880-915 MHz onuplink and 925-960 MHz on downlink), EU R & TTE frequencies (1710-1785MHz on uplink and 1805-1880 MHz on downlink), EU R & TTE frequencies(1920-1980 MHz on uplink and 2110-2170 MHz on downlink), US FCCfrequencies (806-824 MHz on uplink and 851-869 MHz on downlink), US FCCfrequencies (896-901 MHz on uplink and 929-941 MHz on downlink), US FCCfrequencies (793-805 MHz on uplink and 763-775 MHz on downlink), and USFCC frequencies (2495-2690 MHz on uplink and downlink).

With continuing reference to FIG. 2A, the received downlink electricalcommunications signals 208D(1)-208D(S) are provided to a plurality ofoptical interfaces provided in the form of optical interface modules(OIMs) 210(1)-210(W) in this embodiment to convert the downlinkelectrical communications signals 208D(1)-208D(S) into downlink opticalcommunications signals 212D(1)-212D(S). The notation “1-W” indicatesthat any number of the referenced component 1-W may be provided. TheOIMs 210 may include one or more optical interface components (OICs)that contain electrical-to-optical (E-O) converters 216(1)-216(W) toconvert the received downlink electrical communications signals208D(1)-208D(S) into the downlink optical communications signals212D(1)-212D(S). The OIMs 210 support the radio bands that can beprovided by the RIMs 204, including the examples previously describedabove. The downlink optical communications signals 212D(1)-212D(S) arecommunicated over a downlink optical fiber communications link 214D to aplurality of remote units 218(1)-218(X) provided in the form of remoteantenna units in this example. The notation “1-X” indicates that anynumber of the referenced component 1-X may be provided. One or more ofthe downlink optical communications signals 212D(1)-212D(S) can bedistributed to each remote unit 218(1)-218(X). Thus, the distribution ofthe downlink optical communications signals 212D(1)-212D(S) from thecentral unit 206 to the remote units 218(1)-218(X) is in apoint-to-multipoint configuration in this example.

With continuing reference to FIG. 2A, the remote units 218(1)-218(X)include optical-to-electrical (O-E) converters 220(1)-220(X) configuredto convert the one or more received downlink optical communicationssignals 212D(1)-212D(S) back into the downlink electrical communicationssignals 208D(1)-208D(S) to be wirelessly radiated through antennas222(1)-222(X) in the remote units 218(1)-218(X) to user equipment (notshown) in the reception range of the antennas 222(1)-222(X). The OIMs210 may also include O-E converters 224(1)-224(W) to convert thereceived uplink optical communications signals 212U(1)-212U(Y) from theremote units 218(1)-218(X) into the uplink electrical communicationssignals 226U(1)-226U(Y) as will be described in more detail below. Thenotation “1-Y” indicates that any number of the referenced component 1-Ymay be provided.

With continuing reference to FIG. 2A, the remote units 218(1)-218(X) arealso configured to receive uplink electrical communications signals228U(1)-228U(X) received by the respective antennas 222(1)-222(X) fromclient devices in wireless communications range of the remote units218(1)-218(X). The uplink electrical communications signals228U(1)-228U(X) may be analog signals or digital signals that can besampled and processed as digital information. The remote units218(1)-218(X) include E-O converters 229(1)-229(X) to convert thereceived uplink electrical communications signals 228U(1)-228U(X) intouplink optical communications signals 212U(1)-212U(Y). The remote units218(1)-218(X) distribute the uplink optical communications signals212U(1)-212U(Y) over an uplink optical fiber communications link 214U tothe OIMs 210(1)-210(W) in the central unit 206. The O-E converters224(1)-224(W) convert the received uplink optical communications signals212U(1)-212U(Y) into uplink electrical communications signals226U(1)-226U(Y), which are processed by the RIMs 204(1)-204(T) andprovided as the uplink electrical communications signals 230U(1)-230U(Y)to a source transceiver such as a base transceiver station (BTS) orbaseband unit (BBU).

Note that the downlink optical fiber communications link 214D and theuplink optical fiber communications link 214U coupled between thecentral unit 206 and the remote units 218(1)-218(X) may be a commonoptical fiber communications link, wherein for example, wave divisionmultiplexing (WDM) may be employed to carry the downlink opticalcommunications signals 212D(1)-212D(S) and the uplink opticalcommunications signals 212U(1)-212U(Y) on the same optical fibercommunications link. Alternatively, the downlink optical fibercommunications link 214D and the uplink optical fiber communicationslink 214U coupled between the central unit 206 and the remote units218(1)-218(X) may be a single, separate optical fiber communicationslink, wherein for example, WDM may be employed to carry the downlinkoptical communications signals 212D(1)-212D(S) on one common downlinkoptical fiber and the uplink optical communications signals212U(1)-212U(Y) carried on a separate, only uplink optical fiber.Alternatively, the downlink optical fiber communications link 214D andthe uplink optical fiber communications link 214U coupled between thecentral unit 206 and the remote units 218(1)-218(X) may be separateoptical fibers dedicated to and providing a separate communications linkbetween the central unit 206 and each remote unit 218(1)-218(X).

The DCS 200 in FIG. 2A can be provided in an indoor environment asillustrated in FIG. 2B. FIG. 2B is a partially schematic cut-awaydiagram of a building infrastructure 232 employing the DCS 200. FIG. 2Cis a schematic diagram of the DCS 200 installed according to thebuilding infrastructure 232 in FIG. 2B.

With reference to FIG. 2B, the building infrastructure 232 in thisembodiment includes a first (ground) floor 234(1), a second floor234(2), and a Fth floor 234(F), where ‘F’ can represent any number offloors. The floors 234(1)-234(F) are serviced by the central unit 206 toprovide antenna coverage areas 236 in the building infrastructure 232.The central unit 206 is communicatively coupled to a signal source 238,such as a BTS or BBU, to receive the downlink electrical communicationssignals 208D(1)-208D(S). The central unit 206 is communicatively coupledto the remote units 218(1)-218(X) to receive uplink opticalcommunications signals 212U(1)-212U(Y) from the remote units218(1)-218(X) as previously described in FIG. 2A. The downlink anduplink optical communications signals 212D(1)-212D(S), 212U(1)-212U(Y)are distributed between the central unit 206 and the remote units218(1)-218(X) over a riser cable 240 in this example. The riser cable240 may be routed through interconnect units (ICUs) 242(1)-242(F)dedicated to each floor 234(1)-234(F) for routing the downlink anduplink optical communications signals 212D(1)-212D(S), 212U(1)-212U(Y)to the remote units 218(1)-218(X). The ICUs 242(1)-242(F) may alsoinclude respective power distribution circuits 244(1)-244(F) thatinclude power sources as part of the power distribution system 250,wherein the power distribution circuits 244(1)-244(F) are configured todistribute power remotely to the remote units 218(1)-218(X) to providepower for operating the power consuming components (e.g., the radiocommunications circuits) in the remote units 218(1)-218(X). For example,array cables 245(1)-245(2F) may be provided and coupled between the ICUs242(1)-242(F) that contain both optical fibers to provide the respectivedownlink and uplink optical fiber communications links 214D(1)-214D(2F),214U(1)-214U(2F) and power conductors 246(1)-246(2F) (e.g., electricalwire) to carry current from the respective power distribution circuits244(1)-244(F) to the remote units 218(1)-218(X).

With reference to the DCS 200 shown in FIG. 2C, the central unit 206 mayinclude a power supply circuit 252 to provide power to the RIMs204(1)-204(T), the OIMs 210(1)-210(W), and radio distribution circuits(RDCs) 254, 256. The downlink electrical communications signals208D(1)-208D(S) and the uplink electrical communications signals226U(1)-226U(Y) are routed from between the RIMs 204(1)-204(T) and theOIMs 210(1)-210(W) through RDCs 254, 256. In one embodiment, the RDCs254, 256 can support sectorization in the DCS 200, meaning that onlycertain downlink electrical communications signals 208D(1)-208D(S) arerouted to certain RIMs 204(1)-204(T). A power supply circuit 258 mayalso be provided to provide power to the OIMs 210(1)-210(W). Aninterface 260, which may include web and network management system (NMS)interfaces, may also be provided to allow configuration andcommunication to the components of the central unit 206. Amicrocontroller, microprocessor, or other control circuitry, called ahead-end controller (HEC) 262 may be included in central unit 206 toprovide control operations for the central unit 206 and the DCS 200.

As discussed above in reference to FIG. 2B and with continuing referenceto FIG. 2C, the power distribution circuits 244(1)-244(F) may beprovided in the DCS 200 to remotely supply power to the remote units218(1)-218(X) for operation. For example, the power distributioncircuits 244(1)-244(F) may be configured to supply direct current (DC)power due to relatively short distances and as a safer option thandistributing alternating current (AC) power. Further, distributing DCpower may avoid the need to provide AC-DC conversion circuitry in theremote units 218(1)-218(X) saving area and cost. Remotely distributingpower to the remote units 218(1)-218(X) may be desired if it isdifficult or not possible to locally provide power to the remote units218(1)-218(X) in their installed locations. For example, the remoteunits 218(1)-218(X) may be installed in ceilings or on walls of abuilding. Even if local power is available, the local power may not becapable of supplying enough power to provide power to the number ofremote units 218(1)-218(X) desired (e.g., only 50 W of power may beprovided locally when 100 W are needed). However, regulations may alsolimit the amount of DC power that is remotely delivered by the powerdistribution circuits 244(1)-244(F) over the power conductors246(1)-246(2F) to less than the amount needed to power the remote units218(1)-218(X) during peak power consumption periods for safety reasons,such as in the event a human contacts the power conductors246(1)-246(2F). One solution to these remote power distributionlimitations is to employ multiple power conductors 246(1)-246(2F) andsplit current from the power distribution circuits 244(1)-244(F) overthe multiple power conductors 246(1)-246(2F) as shown, such that thecurrent on any one power conductor 246(1)-246(2F) is below the regulatedlimit. Another solution includes delivering remote power at a highervoltage so that a lower current can be distributed at the same powerlevel. For example, assume that 300 W of power is to be supplied to aremote unit 218(1)-218(X) by a power distribution circuit 244(1)-244(F)through a respective power conductor 246(1)-246(2F). If the voltage ofthe power distribution circuit 244(1)-244(F) is 60 Volts (V), thecurrent will be 5 Amperes (A) (i.e., 300 W/60 V). However, if 400 V isemployed, then the current flowing through the wires will be 0.75 A.However, delivering high voltage through power conductors 246(1)-246(2F)may be further regulated to prevent an undesired current from flowingthrough a human in the event that a human contacts the power conductor246(1)-246(2F). Thus, these safety measures may require otherprotections, such as the use of protection conduits for the array cables245(1)-245(2F), which may make installations of the DCS 200 moredifficult and add cost.

As noted above, the power distribution circuit of the present disclosuremay provide power to radio communications circuits that appear in a RAN.An exemplary RAN is discussed herein with reference to FIGS. 3A-3C. Inthis regard, FIG. 3A is a schematic diagram of an exemplary mobiletelecommunications environment 300 (also referred to as “environment300”) that includes exemplary macrocell RANs 302(1)-302(M) (“macrocells302(1)-302(M)”) and an exemplary small cell RAN 304 located within anenterprise environment 306 and configured to service mobilecommunications between a user mobile communications device 308(1)-308(R)(e.g., a cellular phone, laptop, tablet, or the like) to a mobilenetwork operator (MNO) 310. The user mobile communications devices308(1)-308(R) can be configured to discover neighboring radio accesssystems to be reported to a serving RAN. A serving RAN for a user mobilecommunications devices 308(1)-308(R) is a RAN or cell in the RAN inwhich the user mobile communications devices 308(1)-308(R) have anestablished communications session with the exchange of mobilecommunications signals for mobile communications. Thus, a serving RANmay also be referred to herein as a serving cell. For example, the usermobile communications devices 308(3)-308(R) in FIG. 3A are beingserviced by the small cell RAN 304, whereas user mobile communicationsdevices 308(1) and 308(2) are being serviced by the macrocells302(1)-302(M). Each of the macrocells 302(1)-302(M) is an MNO macrocellin this example. However, a shared spectrum RAN 302′ (also referred toas “shared spectrum cell 302”) includes a macrocell in this example andsupports communications on frequencies that are not solely licensed to aparticular MNO and thus may service user mobile communications devices308(1)-308(R) independent of a particular MNO. For example, the sharedspectrum cell 302′ may be operated by a third party that is not an MNOand wherein the shared spectrum cell 302′ support citizens broadbandradio service (CBRS). Also, as shown in FIG. 3A, the MNO macrocell 302,the shared spectrum cell 302′, and the small cell RAN 304 may beneighboring radio access systems to each other, meaning that some or allcan be in proximity to each other such that a user mobile communicationsdevice 308(3)-308(R) may be able to be in communications range of two ormore of the MNO macrocell 302, the shared spectrum cell 302′, and thesmall cell RAN 304 depending on the location of user mobilecommunications devices 308(3)-308(R).

A general principle in environment 300 is that a serving RAN (e.g., aneNB in such system) provides a measurement configuration to the usermobile communications devices 308(1)-308(R) to “point” the receiver ofthe user mobile communications device 308(1)-308(R) to find othersystems (e.g., neighboring cells) transmitting at a specifiedfrequency(ies) (e.g., at 1900 MHz, 2500 MHz) according to themeasurement configuration that the user mobile communications device308(1)-308(R) should measure. The measurement of communications signalsof other RANs by the user mobile communications device 308(1)-308(R) atspecified frequencies is performed for a variety of purposes, includinginter-frequency mobility and inter-frequency measurements. The usermobile communications devices 308(1)-308(R) can find thesecommunications systems and perform actions, such as cell selection inthe idle mode and sending of measurement reports (e.g., MeasurementReport Messages (MRMs)) in the active mode. These measurement reportscan be used by the serving RAN (e.g., MNO macrocell 302, shared spectrumcell 302′, small cell RAN 304) to, for example, trigger handovers or togather information about neighboring cells through Automatic NeighborRelation (ANR) discovery. For example, the MNO macrocell 302 may use theMRMs for cell reselection to cause a user mobile communications device308(1)-308(R) to be serviced by a different cell controlled by the MNO,such as the small cell RAN 304 for example, for optimizingcommunications. In idle mode, this measurement report information isdelivered in a System Information broadcast, which is used by the MNOmacrocell 302 to indicate, point out, and/or determine systems andfrequencies in the pertinent area. This measurement report informationis delivered in user mobile communications device-specific radioresource control signaling messages to serviced user mobilecommunications devices 308(1)-308(R) that indicate to the user mobilecommunications devices 308(1)-308(R) the appropriate measurementconfiguration parameters. In these measurement configuration parameters,there are specific instructions about what frequencies the serviced usermobile communications device 308(1)-308(R) should measure. Theinformation measured by the user mobile communications devices308(1)-308(R) is then reported back to the serving RAN. For example, theMNO macrocell 302 as a serving RAN may use the measurement reportinformation to determine if other systems of higher priority exist.

In this regard, with continuing reference to FIG. 3A, the user mobilecommunications device 308(1) is shown being serviced by the MNOmacrocell 302. However, the user mobile communications device 308(1) maybe in communications range of the shared spectrum cell 302′. As anotherexample, the user mobile communications device 308(3) shown beingserviced by the small cell RAN 304 in FIG. 3A may also be incommunications range of the MNO macrocell 302 and/or the shared spectrumcell 302′. As an example, the MNO macrocell 302 may be unaware of thefrequency bands used by the other neighboring RANs, such as the sharedspectrum cell 302′. Thus, the MNO macrocell 302 as the serving RAN tothe user mobile communications device 308(3) may be unaware of whatspecific frequencies to point the user mobile communications device308(3) to for discovery. In this regard, as an example, the user mobilecommunications devices 308(1)-308(R) serviced by their respectiveserving RANs may be configured to tune its receiver to scan one or morefrequency ranges (e.g., bands) based on a scan frequency criteria todiscover other neighboring radio access systems in communications rangeof the user mobile communications device 308(1)-308(R). In this example,the scan frequency criteria do not include solely a pre-knowntransmission frequency for the one or more neighboring radio accesssystems. However, note that frequency range based on the scan frequencycriteria can include a center transmission frequency (e.g., an EARFCN)of a neighboring radio access system, but is not solely comprised of acenter transmission frequency of a neighboring radio access system. Thisis opposed to, for example, the user mobile communications device308(1)-308(R) only searching for transmitted communications signals at aspecific center frequency, such as for example, using a specific EvolvedUniversal Terrestrial Radio Access (E-UTRA) Absolute Radio FrequencyChannel Number (EARFCN). Any neighboring radio access systems discoveredby the user mobile communications device 308(1)-308(R) according to thescanned frequency band(s) can be reported to its serving RAN in ameasurement report.

With continued reference to FIG. 3A, the mobile telecommunicationsenvironment 300 in this example, is arranged as a Long Term Evolution(LTE) system as described by the Third Generation Partnership Project(3GPP) as an evolution of the Global System for Mobilecommunication/Universal Mobile Telecommunications System (GSM/UMTS)standards. It is emphasized, however, that the aspects described hereinmay also be applicable to other network types and protocols. The mobiletelecommunications environment 300 includes the enterprise environment306 in which the small cell RAN 304 is implemented. The small cell RAN304 includes a plurality of small cell radio nodes (RNs) 312(1)-312(C).Each small cell radio node 312(1)-312(C) has a radio coverage area(graphically depicted in the drawings as a hexagonal shape) that iscommonly termed a “small cell.” A small cell may also be referred to asa femtocell, or using terminology defined by 3GPP as a Home Evolved NodeB (HeNB). In the description that follows, the term “cell” typicallymeans the combination of a radio node and its radio coverage area unlessotherwise indicated.

The size of the enterprise environment 306 and the number of cellsdeployed in the small cell RAN 304 may vary. In typical implementations,the enterprise environment 306 can be from 50,000 to 500,000 square feetand encompass multiple floors, and the small cell RAN 304 may supporthundreds to thousands of users using mobile communications platformssuch as mobile phones, smartphones, tablet computing devices, and thelike shown as the user mobile communications devices 308(3)-308(R).However, the foregoing is intended to be illustrative and the solutionsdescribed herein can be typically expected to be readily scalable eitherupwards or downwards as the needs of a particular usage scenario demand.

In FIG. 3A, the small cell RAN 304 includes one or more services nodes(represented as a single services node 314 in FIG. 3A) that manage andcontrol the small cell radio nodes 312(1)-312(C). In alternativeimplementations, the management and control functionality may beincorporated into a radio node, distributed among nodes, or implementedremotely (i.e., using infrastructure external to the small cell RAN304). The small cell radio nodes 312(1)-312(C) are coupled to theservices node 314 over a direct or local area network (LAN) connection316 as an example typically using secure IPsec tunnels. The servicesnode 314 aggregates voice and data traffic from the small cell radionodes 312(1)-312(C) and provides connectivity over an IPsec tunnel to asecurity gateway (SeGW) 318 in an Evolved Packet Core (EPC) network 320of the MNO 310. The EPC network 320 is typically configured tocommunicate with a public switched telephone network (PSTN) 322 to carrycircuit-switched traffic, as well as for communicating with an externalpacket-switched network such as the Internet 324.

The environment 300 also generally includes an Evolved Node B (eNB) basestation, or “macrocell” 302. The radio coverage area of the macrocell302 is typically much larger than that of a small cell where the extentof coverage often depends on the base station configuration andsurrounding geography. Thus, a given user mobile communications device308(3)-308(R) may achieve connectivity to the EPC network 320 througheither a macrocell 302 or small cell radio node 312(1)-312(C) in thesmall cell RAN 304 in the environment 300.

It should be appreciated that there are myriad places where adistributed power network may be employed in the environment 300. Inparticular, a power distribution source 330 may be present at servicesnode 314 and distribute power to power sinks 332(1)-332(C) in the smallcell radio nodes 312(1)-312(C) through appropriate conductors (notshown). Alternatively, a separate power distribution source 330′ may bepresent and distribute power to power sinks 332(1)-332(C) in the smallcell radio nodes 312(1)-312(C). Still further, a power distributionsource 334 may be associated with the macrocells 302(1)-302(M) andprovide power to power sinks 336 in the macrocells 302. Still otherpower distribution networks may be present in the environment 300, anddifferent elements within the environment 300 may be considered radiocircuits.

Along with macrocell 302, the small cell RAN 304 forms an access network(i.e., an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN)) under3GPP as represented by reference numeral 340 in FIG. 3B. As shown inFIG. 3B, there is no centralized controller in the E-UTRAN 340, hence anLTE network architecture is commonly said to be “flat.” Macrocells302(1)-302(M) are typically interconnected using an X2 interface 342.The shared spectrum cell 302′ may or may not be interconnected to themacrocells 302(1)-302(M) through the X2 interface 342. The macrocells302(1)-302(M) and shared spectrum cell 302′ are also typically connectedto the EPC network 320 by means of an S1 interface 344. Moreparticularly, the macrocells 302(1)-302(M) and the shared spectrum cell302′ are connected to a Mobility Management Entity (MME) 346 in the EPCnetwork 320 using an S1-MME interface 348, and to a Serving Gateway(S-GW) 350 using an S1-U interface 352. An S5/S8 interface 354 couplesthe S-GW 350 to a Packet Data Network Gateway (P-GW) 356 in the EPCnetwork 320 to provide the user mobile communications devices308(1)-308(R) with connectivity to the Internet 324. A user mobilecommunications device 308(1)-308(R) can connect to the small cell radionodes 312(1)-312(C) in the small cell RAN 304 over an LTE-Uu interface358.

The S1-MME interface 348 is also connected to the MME 346 and S-GW 350in the EPC network 320 using the appropriate S1 interface connections344. Accordingly, as each of the small cell radio nodes 312(1)-312(C) inthe small cell RAN 304 is operatively coupled to the services node 314over the LAN connection 316, the communications connections from thesmall cell radio nodes 312(1)-312(C) are aggregated to the EPC network320. Such aggregation preserves the flat characteristics of the LTEnetwork while reducing the number of S1 interface connections 344 thatwould otherwise be presented to the EPC network 320. Thus, the smallcell RAN 304 essentially appears as a single eNB 360 to the EPC network320, as shown. The services node 314 in the small cell RAN 304 includesa central scheduler 362. The small cell radio nodes 312(1)-312(C) mayalso be configured to support individual schedulers 364.

A user mobile communications device 308 connected to the environment 300will actively or passively monitor a cell in a macrocell 302(1)-302(M)in the E-UTRAN 340 in the communications range of the user mobilecommunications device 308 as the user mobile communications device 308moves throughout the environment 300. As shown in FIG. 3C, such a cellis termed the “serving cell.” For example, if user mobile communicationsdevice 308 is in communication through an established communicationssession with a particular small cell radio node 312(1)-312(C) in thesmall cell RAN 304, the particular small cell radio node 312(1)-312(C)will be the serving cell to the user mobile communications device 308,and the small cell RAN 304 will be the serving RAN. The user mobilecommunications device 308 will continually evaluate the quality of aserving cell as compared with that of a neighboring cell 370 in thesmall cell RAN 304, MNO macrocells 302, and/or the shared spectrum cell302′, as shown in FIG. 3C. A neighboring cell 370 is a cell among thesmall cell RAN 304, MNO macrocells 302, and/or the shared spectrum cell302′ that is not in control of the active communications session for agiven user mobile communications device 308, but is located in proximityto a serving cell to a user mobile communications device 308 such thatthe user mobile communications device 308 could be in communicationsrange of both its serving cell and the neighboring cell 370. Each of thesmall cell radio nodes 312(1)-312(C), the macrocells 302(1)-302(M), andthe shared spectrum cell 302′ can identify themselves to a user mobilecommunications device 308 using a respective unique Physical CellIdentity (PCI) 372(1)-372(M), 374, 376(1)-376(C) (e.g., a public landmobile network (PLMN) identification (ID) (PLMN ID)) that is transmittedover a downlink user mobile communications device 308. Each of the smallcell radio nodes 312(1)-312(C), the MNO macrocells 302(1)-302(M), andthe shared spectrum cell 302′ can assign a PCI that allows a user mobilecommunications device 308 to distinguish adjacent cells. As such, thePCIs 372(1)-372(M), 374, 376(1)-376(C) are uniquely assigned amongneighboring cells 370, but can be reused across geographically separatedcells.

As discussed above, a general principle in the E-UTRAN 340 in FIGS.3A-3C is that a serving RAN (e.g., an eNB in such system) provides ameasurement configuration to the user mobile communications devices308(1)-308(R) to “point” the receiver of the user mobile communicationsdevice 308(1)-308(R) to find other neighboring cells 370 transmitting ata specified frequency(ies) (e.g., at 1900 MHz, 2500 MHz) according tothe measurement configuration that the user mobile communications device308(1)-308(R) should measure. However, new mobile access systems arecapable of supporting spectrums independent of an MNO, such as theshared spectrum cell 302′ in FIGS. 3A-3C. For example, the sharedspectrum cell 302′ may support a spectrum that includes an unlicensedspectrum, a shared spectrum, a spectrum licensed from a third party,and/or a spectrum associated with citizens broadband radio service(CBRS), and so on. In these cases, spectrum allocation, or channelallocation, may be assigned for the shared spectrum cell 302′ by atechnique or procedures that occur independently of the MNO thatcontrols the MNO macrocells 302(1)-302(M), such as a Spectrum AllocationSystem (SAS) for example. As an example, if the shared spectrum cell302′ were a CBRS system operated in a stadium or arena by a third party,such shared spectrum cell 302′ may be dynamically assigned a channel bya SAS. Due to this independent and dynamic nature of spectrumallocation, it would be very difficult for all surrounding MNOmacrocells 302(1)-302(M) to be constantly aware of all the actualfrequencies in which the shared spectrum cell 302′ was allocated andoperated on. However, if the third party has a business agreement withan MNO, the shared spectrum cell 302′ may be configured to serve usermobile communications devices 308(1)-308(R) associated with a specificMNO or a specific set of MNOs supported by the MNO macrocells302(1)-302(M). In so doing, the shared spectrum cell 302′ isbroadcasting the PCIs 372(1)-372(M) of the associated MNO macrocells302(1)-302(M) to enable connections to user mobile communicationsdevices 308(1)-308(R). Even with the business relationship between theMNOs of the MNO macrocells 302(1)-302(M) and the operator of the sharedspectrum cell 302′, the MNOs may be completely unaware of the specificfrequencies allocated by the SAS to the shared spectrum cell 302′ forcommunications. Even if the third party was made aware of such frequencyallocation, this allocation may change dynamically due to steps taken bythe shared spectrum cell 302′ SASs for frequency optimization or otherpurposes. Thus, it is difficult and undesirable for the shared spectrumcell 302′ to update each MNO with a list of employed, allocatedfrequencies. Such updating would create undesired operational couplingbetween the shared spectrum cell 302′ and the MNO macrocells302(1)-302(M).

The present disclosure is designed to provide power to radiocommunications circuits in any of these (or other) communicationssystems. Thus, the radio communications circuits may be macrocells,remote units, remote antenna units, RAN, shared spectrum cells that uselicensed or unlicensed bandwidth, small cell radio nodes, head endunits, remote radio units, remote radio heads, and the like.

Against the backdrop the various communications environments that mayinclude a power distribution system, a discussion of exemplary aspectsof the power distribution system of the present disclosure now begins.In this regard, FIG. 4 is a schematic diagram illustrating a powerdistribution circuit 244 of the power distribution system 250 in theform of the DCS 200 in FIGS. 2A-2C. It should be appreciated that theconcepts are equally applicable to environment 300. The powerdistribution circuit 244 in FIG. 4 can be any of the power distributioncircuits 244(1)-244(F) in FIGS. 2B and 2C or the power distributioncircuits (e.g., power distribution source 330) of FIGS. 3A-3C. The powerdistribution circuit 244 includes a power source 400 that is configuredto supply power (i.e., current I₁) to be distributed over the powerconductors 246+, 246− to a load 401 of the remote unit 218 to providepower to at least radio communications circuits within the remote unit218 for operation of its power consuming components. For example, thepower source 400 may be a DC/DC power supply (e.g., 48 V DC/350 V DC) orAC/DC power supply (e.g., AC/350 V DC). The power source 400 may beincluded in the same housing or chassis as the power distributioncircuit 244, or separate from the power distribution circuit 244. Aswill be discussed in more detail below, the power distribution circuit244 illustrated in FIG. 4 is configured to provide a safety powerdisconnect of the power source 400 from the power conductors 246+, 246−in response to a measured current I₂ from the connected power source 400when the remote unit 218 is decoupled from the power source 400 during atesting phase. The power distribution circuit 244 includes a currentmeasurement circuit 402 configured to measure the current I₂ deliveredby the power source 400 to a distribution power output 403 coupled tothe power conductors 246+, 246− as an indication of a safety conditionas to whether an external load, such as a human, is in contact on thepower conductors 246+, 246−. If another load is not contacting the powerconductors 246+, 246−, this means no current or only a small amount ofcurrent, due to current leakages for example, should flow from the powersource 400 to the power conductors 246+, 246−. However, if an externalload 418, such as a person, is contacting the power conductors 246+,246−, this load 418 will present a load to the power source 400 thatwill cause the current I₂ to flow from the power source 400 over thepower conductors 246+, 246−. This current I₂ can be detected as a methodof detecting an external load 418, such as a human, in contact with thepower conductors 246+, 246− to cause the power distribution circuit 244to decouple the power source 400 from the power conductors 246+, 246− asa safety measure.

In this regard, in a first exemplary aspect, with reference to FIG. 4,the power distribution circuit 244 includes a controller circuit 404.The controller circuit 404 is configured to send a distribution powerconnection control signal 406 indicating a distribution power connectionmode to close a distribution switch circuit 408 to couple the powersource 400 to the current measurement circuit 402. The closing of thedistribution switch circuit 408 allows current I₁ to be drawn from thepower source 400 and be carried by the power conductor 246+ to a remotepower input 409 of the remote unit 218. To determine if an external load418 other than the remote unit 218, such as a human, is contacting thepower conductors 246+, 246−, the controller circuit 404 could beconfigured to communicate over a management communications link 410 tothe remote unit 218. The management communications link 410 may beelectrical conductors (e.g. copper wire) or an optical fiber medium asexamples. The management communications link 410 may be a bidirectionalcommunications link configured to carry a full duplex signal at acarrier frequency, such as 1.5 MHz for example. The controller circuit404 is configured to send a remote power connection signal 412indicating a remote power disconnect state to a switch control circuit414 coupled to the management communications link 410. In response, theswitch control circuit 414 is configured to send a remote powerconnection signal 411 indicating the remote power disconnect state to aremote switch input 413 to open a remote switch circuit 416 in theremote unit 218 to decouple the remote unit 218 from power conductor246+, thereby disconnecting the load of the remote unit 218 from thepower distribution circuit 244. This allows a measurement current on thepower conductors 246+, 246− to be associated with an external load 418and not the load of the remote unit 218. When the remote switch circuit416 is open, power is provided to the load 401 from the capacitor C₁.The current measurement circuit 402 measures the current on the powerconductors 246+, 246− while the remote unit 218 is decoupled from thepower source 400. If an external load 418 is not contacting the powerconductors 246+, 246−, this means no current (or only a small amount ofcurrent due to current leakages for example) should flow from the powersource 400 to the power conductors 246+, 246−. However, if an externalload 418, such as a person, is contacting the power conductors 246+,246−, this load 418 will present a load to the power source 400 thatwill cause current I₂ to flow from the power source 400 over the powerconductors 246+, 246−. Any measured current I₂ by the currentmeasurement circuit 402 is communicated to the controller circuit 404.In response to detection of the external load 418 as a function of themeasured current I₂ exceeding a predefined threshold current level, thecontroller circuit 404 is configured to communicate the distributionpower connection control signal 406 indicating a distribution powerdisconnect state to the distribution switch circuit 408 to disconnectthe power source 400 from the power conductors 246+, 246− for safetyreasons. This is because the external load 418 applied to the powerconductors 246+, 246− to cause the current I₂ to flow from the powersource 400 may be a human contacting the power conductors 246+, 246−.

Note that the management communications link 410 can be a separatecommunications link from the power conductors 246+, 246− or a modulatedsignal coupled to the power conductors 246+, 246− such that the remotepower connection signal 412 is modulated with power over the powerconductors 246+, 246−. If the management communications link 410 isprovided as a separate communications link, the managementcommunications link 410 may be electrical conducting wire, such ascopper wires for example. The management communications link 410 couldalso carry power to the switch control circuit 414 to power the switchcontrol circuit 414 since the management communications link 410 iscoupled to the switch control circuit 414. For example, the predefinedthreshold current level may be based on the voltage of the power source400 and an estimated 2,000 Ohms resistance of a human. For example, theInternational Electric Code (IEC) 60950-21 entitled “Remote PoweringRegulatory Requirements” provides that for a 400 V DC maximumline-to-line voltage, the human body resistance from hand to hand isassumed to be 2,000 Ohms resulting in a body current of 200 mA. Theremote unit 218 is eventually recoupled to the power source 400 to onceagain be operational.

After the controller circuit 404 communicates the distribution powerconnection control signal 406 indicating the distribution powerdisconnect state to the distribution switch circuit 408 to disconnectthe power source 400 from the power conductors 246+, 246−, thecontroller circuit 404 can be configured to wait a period of time and/oruntil a manual reset instruction is received before recoupling the powersource 400 to the remote unit 218. In this regard, the controllercircuit 404 can communicate the distribution power connection controlsignal 406 indicating a distribution power connect state to thedistribution switch circuit 408 to cause the distribution switch circuit408 to be closed to couple the power source 400 to the power conductors246+, 246−. The controller circuit 404 can also send the remote powerconnection signal 412 indicating a remote power connect state to theswitch control circuit 414 to generate the remote power connectionsignal 411 to cause the remote switch circuit 416 in the remote unit 218to be closed to once again couple the remote unit 218 to the powerconductor 246+, thereby connecting the load of the remote unit 218 tothe power distribution circuit 244. The capacitor C₁ in the remote unit218 is charged by the power source 400 when the remote unit 218 iscoupled to the power conductors 246+, 246−. The energy stored in thecapacitor C₁ allows the remote unit 218 to continue to be powered duringa testing phase when the remote switch circuit 416 is open. The periodof time in which the remote switch circuit 416 is open is such that thedischarge of the energy stored in the capacitor C₁ is sufficient topower the remote unit 218. A resistor R₁ is coupled across the remoteswitch circuit 416 to allow multiple drops/remote units 218 to beconnected to the same remote power input 409. The overall equal parallelresistances can be higher than the body/touch resistance ofapproximately 2 kOhms. The resistance of the resistor R₁ can beincreased by reducing capacitance of the capacitor C₁ to allow a fastercharging time. Powering the switch control circuit 414 in the remoteunit 218 from the management communications link 410 could avoid theneed or desire to include resistor R₁ as the switch control circuit 414would be capable of powering on faster and thus also synchronizing tothe power distribution circuit 244 faster. With continuing reference toFIG. 4, note that an optional current limiter circuit 420 can beprovided in the remote unit 218 and coupled to the remote switch circuit416. The current limiter circuit 420 is configured to limit and avoid anin-rush current, which may be identified by the power distributioncircuit 244 as an overload. This can cause the controller circuit 404 inthe power distribution circuit 244 to send a remote power connectionsignal 411 indicating the remote power disconnect state to a remoteswitch input 413 to open a remote switch circuit 416 in the remote unit218 to decouple the remote unit 218 from power conductor 246+, therebydisconnecting the load of the remote unit 218 from the powerdistribution circuit 244. A DC/DC converter 421 in the remote unit 218can convert a high voltage from the power source 400 (e.g., 400 V) tothe required operation voltage of the load 401 (e.g. 48 V). A power line423 can be provided on the output side of the DC/DC converter 421 toprovide an operational voltage to the switch control circuit 414 foroperation. An optional load switch circuit 425 can also be providedbetween the current limiter circuit 420 and the load 401 to connect anddisconnect the load 401 from the power conductors 246+, 246−. Forexample, the load switch circuit 425 may be under control of thecontroller circuit 404.

In an alternative embodiment, the load switch circuit 425 can be locallycontrolled by the switch control circuit 414 by a pulse width modulated(PWM) signal for example instead of being controlled by the remote powerconnection signal 412. The PWM rate is set by the switch control circuit414 to 0% initially. The switch control circuit 414 can graduallyincrease the PWM rate from 0% to 100% to control in-rush current. Thiscan also allow the current limiter circuit 420 to be eliminated, ifdesired, but elimination or presence is not required.

In this example in FIG. 4, a fast distribution power connection controlsignal 406 is employed that is implemented at a lower protocol level forthe efficiency of the power transfer, as it allows shorter loaddisconnect time, as the power transfer is done during the loadconnecting time. A management signal that is implemented at higherprotocol level is subjected to relatively high delay variations. In oneexample, the distribution power connection control signal 406 isimplemented in the physical level only to minimize possible delayvariation or jitter. An improved timing synchronization between thecontroller circuit 404 and the load disconnect control may allow ashorter load disconnecting time needed for the controller circuit 404 tocheck for lower current detection. In case of high delay variation, thedisconnect time should be larger to ensure additional margin to allowcurrent measurement to be conducted when there is higher confidence thatthe load 401 is disconnected.

In addition, the power distribution circuit 244 may include amultiplexer or combiner 450 that may perform frequency divisionmultiplexing (FDM). Similarly, the remote unit 218 may include amultiplexer or combiner 452 that also uses FDM.

FIG. 5 is a timing diagram 500 illustrating an exemplary timing sequence502 of the controller circuit 404 in the power distribution circuit 244in the DCS 200 in FIG. 4 causing the power source 400 to be coupled tothe remote unit 218 for normal operation, and causing the power source400 to be decoupled from the remote unit 218 in a testing operation todetect the external load 418 in contact with the power conductors 246+,246−. As shown in FIG. 5, a line voltage 503 on the power conductors246+, 246− remains high until the distribution switch circuit 408 opensas explained below. Further, the remote power connect state and remotepower disconnect state of the remote switch circuit 416 as controlled bythe controller circuit 404 is shown as “CLOSE” states starting at timesT₀, T₂, T₄, T₆, etc. in normal operation phases and “OPEN” statesstarting at times T₁, T₃, T₅, T₇, etc. in testing phases. The period oftime between times T₁-T₂, T₃-T₄, and T₅-T₆ when the remote switchcircuit 416 is open is controlled such that energy stored in thecapacitor C₁ when the remote switch circuit 416 is closed is sufficientto power the remote unit 218 during the testing phases. The currentmeasurement circuit 402 measures the current I₂ flowing through thepower conductors 246+, 246− in FIG. 4. To avoid leakage, in one example,the capacitor C₁ can be charged with a low current when the remoteswitch circuit 416 is open, meaning off. Once capacitor C₁ is charged toa high enough voltage such that the switch control circuit 414 canidentify the remote power connection signal 412, the remote switchcircuit 416 can be turned on and off periodically as discussed above.

Between times T₁-T₂, T₃-T₄, and T₅-T₆, when the remote switch circuit416 is open decoupling the remote unit 218 from the power conductors246+, 246−, the controller circuit 404 detects no current flowing as anindication that the external load 418 is not contacting the powerconductors 246+, 246−. However, as shown in FIG. 5, after time T₇, thecurrent measurement circuit 402 measures a current I₂ which is detectedby the controller circuit 404, which is indicative of the external load418 being in contact with the power conductors 246+, 246−. If thecontroller circuit 404 detects the current I₂ exceeding the predefinedthreshold current level, this indicates the external load 418 being incontact with the power conductors 246+, 246−. The controller circuit 404detects the current I₂ exceeding the predefined threshold current levelshown at 504 in FIG. 5 within the detection time 506. In response, asshown in FIG. 5, the controller circuit 404 will communicate thedistribution power connection control signal 406 indicating adistribution power disconnect state to the distribution switch circuit408 to cause the distribution switch circuit 408 to be opened todecouple the power source 400 from the power conductors 246+, 246− forsafety reasons.

Turning back to FIG. 4, the power distribution circuit 244 includes apositive distribution power input 422I(P) configured to receive currentdistributed by the power source 400. A negative distribution power input422I(N) provides a return path for the current. The power distributioncircuit 244 also includes a distribution power output 4220 configured todistribute the received current over the power conductor 246+ coupled tothe remote unit 218. The remote unit 218 coupled to the powerdistribution circuit 244 is deemed assigned to the power distributioncircuit 244. The distribution switch circuit 408 is coupled between thepositive distribution power input 422I(P) and the distribution poweroutput 4220. The distribution switch circuit 408 includes a distributionswitch control input 4241 configured to receive the distribution powerconnection control signal 406 indicating the distribution powerconnection mode, which is either a distribution power connect state or adistribution power disconnect state. For example, the distribution powerconnection mode may be indicated by a bit in the distribution powerconnection control signal 406, where a ‘1’ bit is a distribution powerconnect state and a ‘0’ bit is a distribution power disconnect state, orvice versa. The distribution switch circuit 408 is configured to beclosed to couple the positive distribution power input 422I(P) to thedistribution power output 4220 in response to the distribution powerconnection mode of the distribution power connection control signal 406indicating the distribution power connect state. The distribution switchcircuit 408 is further configured to be opened to decouple the positivedistribution power input 422I(P) from the distribution power output 4220in response to the distribution power connection mode of thedistribution power connection control signal 406 indicating thedistribution power disconnect state.

With continuing reference to FIG. 4, the current measurement circuit 402of the power distribution circuit 244 is coupled to the distributionpower output 422O. The current measurement circuit 402 includes acurrent measurement output 426O. The current measurement circuit 402 isconfigured to measure a current at (i.e., flowing to) the distributionpower output 422O and generate a current measurement 428 on the currentmeasurement output 426O based on the measured current at thedistribution power output 422O. The power distribution circuit 244 alsoincludes a distribution management communications output 432O coupled tothe management communications link 410, which is coupled to the assignedremote unit 218. The controller circuit 404 includes a currentmeasurement input 434I communicatively coupled to the currentmeasurement output 426O of the current measurement circuit 402.

In an alternative embodiment, with reference to FIG. 4, the need toprovide the management communications link 410 between the controllercircuit 404 in the power distribution circuit 244 and the remote unit218 to send the remote power connection signal 412 indicating a remotepower disconnect state to a switch control circuit 414 in the remoteunit 218 can be avoided to provide a more elegant solution. Thissolution may allow the elimination of the remote power connection signal412 as well as any media dedicated to conveying such signal 412. Thus,for example, the remote unit 218 could be configured to cause the switchcontrol circuit 414 (or the switch control circuit 414 itself could beconfigured) periodically to open the remote switch circuit 416 todecouple the remote unit 218 from power conductor 246+, therebydisconnecting the load of the remote unit 218 from the powerdistribution circuit 244. The switch control circuit 414 may have aninternal timer that causes the switch control circuit 414 to open andclose the remote switch circuit 416 periodically. In an exemplary aspectthe internal timer may have a period of four milliseconds (4 ms) and theremote switch circuit 416 may be open (i.e., disconnecting the load 401from the power conductors 246+, 246−) for 0.5 ms of the 4 ms period.Other periods and disconnection windows may be used without departingfrom the present disclosure. If there are multiple cascaded remote units(as discussed in greater detail below with reference to FIG. 8), theremote units may initially synchronize such disconnect windows.

There are two ways that the current measurement circuit 402 can beactivated at the appropriate time (i.e., during a disconnect window). Ina first exemplary aspect, the remote unit 218 and/or the switch controlcircuit 414 can synchronize to the controller circuit 404 generating thedistribution power connection control signal 406 to the distributionswitch circuit 408 to disconnect the power source 400 from the powerconductors 246+, 246−. For example, the switch control circuit 414 inthe remote unit 218 can be configured to monitor changes in current I₁on the power conductor 246+. The current I₁ will drop each time thedistribution switch circuit 408 disconnects the power source 400 fromthe power conductors 246+, 246−, thereby disconnecting the load of theremote unit 218 from the power distribution circuit 244. For example,the controller circuit 404 can be configured to disconnect the remoteunit 218 every 4 ms. It should be appreciated that other periods may beselected without departing from the present disclosure. The remoteswitch circuit 416 can synchronize to this periodic disconnection eventin a short period of time. Thus, if the switch control circuit 414 doesnot see a current drop on power conductor 246+ within a predefinedperiod of time when expected according to the expected periodicdisconnect time according to the timing determined by thesynchronization process, the switch control circuit 414 can open theremote switch circuit 416 to decouple the remote unit 218 from powerconductor 246+, thereby disconnecting the load of the remote unit 218from the power distribution circuit 244. The switch control circuit 414can close the remote switch circuit 416 to recouple the remote unit 218to the power conductor 246+, thereby connecting the load of the remoteunit 218 from the power distribution circuit 244 based on the expectedtiming of when the power distribution circuit 244 will close thedistribution switch circuit 408 according to the timing determined bythe synchronization process. The discussion of further operation of thepower distribution circuit 244 and the remote unit 218 discussed abovefor measuring current on the power conductors 246+, 246− is alsoapplicable for this embodiment.

Instead of the remote unit 218 adapting to drops in the current on thepower conductors 246+, 246−, the second approach would be for the remoteunit 218 to be programmed to disconnect periodically independent of anysignaling from the power distribution circuit 244. The controllercircuit 404 may adaptively learn the period with which the remote unit218 decouples the load 401. Once this period is learned by thecontroller circuit 404, the controller circuit 404 may then instruct thecurrent measurement circuit 402 to measure current in the windows whenthe load 401 is decoupled.

Instead of the controller circuit 404 learning the period of the remoteunit 218, the controller circuit 404 may use a “sliding window” (e.g., a4 ms window), where in situations with no leakage, during every window,there should be at least one drop of the current to a level below theleakage threshold current. In the event that there is no current dropinside the last window, the controller circuit 404 infers leakage anddisconnects power from the conductors 246+, 246− (e.g., controllercircuit 404 issues the distribution power connection control signal 406to open the distribution switch circuit 408). It should be appreciatedthat the leakage threshold current may be set at a variety of levels andmay be, for example, 4 mA, 15 mA, 25 mA, 100 mA, or even 200 mA.

In an alternative embodiment, the power distribution circuit 244 maystill signal to the remote unit 218 that a disconnect is needed, butthis signal is not sent on a separate management communications link 410between the controller circuit 404 in the power distribution circuit244. Thus, the controller circuit 404 could be configured toperiodically drop the output voltage on the power conductor 246+ to aknown voltage level (e.g., from 350 V DC to 300 V DC) beforecommunicating the distribution power connection control signal 406indicating a distribution power disconnect state to the distributionswitch circuit 408 to cause the distribution switch circuit 408 to beopened to decouple the power source 400 from the power conductors 246+,246−. The remote unit 218 and/or the switch control circuit 414 thereincan be configured to monitor the voltage on the power conductor 246+ toidentify this voltage drop as a remote power connection signal 412indicating a remote power disconnect state. In response, the switchcontrol circuit 414 can open the remote switch circuit 416 to decouplethe remote unit 218 from the power conductor 246+, thereby disconnectingthe load 401 of the remote unit 218 from the power distribution circuit244. The remote unit 218 and/or the switch control circuit 414 can waita predefined period of time to close the remote switch circuit 416 torecouple the remote unit 218 to the power conductor 246+, therebyconnecting the load 401 of the remote unit 218 to the power distributioncircuit 244 based on the expected timing of when the power distributioncircuit 244 will close the distribution switch circuit 408 according tothe timing determined by the synchronization process. The discussion offurther operation of the power distribution circuit 244 and the remoteunit 218 discussed above for measuring current on the power conductors246+, 246− is also applicable for this embodiment.

As shown in the exemplary process 600 in FIG. 6 referencing the DCS 200in FIG. 4, in one example option, the controller circuit 404 isconfigured to communicate the remote power connection signal 412comprising a remote power connection mode indicating a remote powerdisconnect state over the distribution management communications output432O coupled to the assigned remote unit 218 to cause the remote switchcircuit 416 to open and decouple the remote unit 218 from the powerconductor 246+ carrying the current I₁ (block 602 in FIG. 6). Thecontroller circuit 404 is also configured to measure a current I₂received from the power source 400 coupled to the power conductor 246+(block 604 in FIG. 6). The controller circuit 404 is configured todetermine if the measured current I₂ on the current measurement input434I exceeds a predefined threshold current level (block 606 in FIG. 6).In response to the measured current I₂ exceeding the predefinedthreshold current level indicating that the external load 418 iscontacting the power conductor 246+ or 246−, the controller circuit 404is configured to communicate the distribution power connection controlsignal 406 comprising the distribution power connection mode indicatingthe distribution power disconnect state to the distribution switchcontrol input 424I to cause the distribution switch circuit 408 to opento decouple the power source 400 from the current measurement circuit402 and the power conductor 246+ (block 608 in FIG. 6). For example, thepredefined threshold current level may be less than or equal to 200 mAor less than or equal to 100 mA, as examples. If instead, the measuredcurrent I₂ of the power distribution circuit 244 does not exceed thepredefined threshold current level, the controller circuit 404 isconfigured to communicate the distribution power connection controlsignal 406 to provide the distribution power connection mode indicatingthe distribution power connect state to the distribution switch controlinput 4241. This causes the distribution switch circuit 408 to close orcontinue to be closed and couple or continue to couple the power source400 to the current measurement circuit 402 and the power conductor 246+for providing power to the remote unit 218.

With continuing reference to FIG. 4, in instantiations where thecontroller circuit 404 controls the operation of the remote switchcircuit 416, the controller circuit 404 is also configured tocommunicate the remote power connection signal 412 comprising the remotepower connection mode indicating the remote power disconnect state overthe distribution management communications output 432O beforedetermining if the measured current I₂ on the current measurement input434I exceeds a predefined threshold current level. This causes theremote switch circuit 416 to open to decouple the remote unit 218 fromthe power conductor 246+ or 246−. This is so that when it is desired totest to determine if the external load 418 is contacting the powerconductor 246+ or 246−, the remote unit 218 is decoupled from the powerconductor 246+ or 246− so that the load 401 of the remote unit 218 isnot causing a current to be drawn from the power source 400. In thismanner, any measured current I₂ on the current measurement input 434I isan indication of the external load 418 contacting the power conductor246+ or 246− and not the load 401 of the remote unit 218. As previouslydiscussed, the energy stored in the capacitor C₁ when the remote unit218 is coupled to the power conductor 246+ or 246− allows the remoteunit 218 to continue to be powered during the testing phase when theremote switch circuit 416 is open.

With continuing reference to FIG. 4, after the testing phase, thecontroller circuit 404 after a predefined period of time is configuredto communicate the remote power connection signal 412 with a remotepower connection mode indicating a remote power connect state over thedistribution management communications output 432O and over themanagement communications link 410. This causes the remote switchcircuit 416 to close so that the remote unit 218 is again coupled to thepower conductor 246+ to receive power from the power distributioncircuit 244. The controller circuit 404 may be configured to communicatethe remote power connection signal 412 with a remote power connectionmode indicating a remote power connect state over the distributionmanagement communications output 432O after a predefined period of timehas elapsed communicating the remote power connection signal 412 with aremote power connection mode indicating a remote power disconnect state.The controller circuit 404 may be configured to initially communicatethe remote power connection signal 412 of the remote power connectionmode indicating the remote power connect state before communicating theremote power connection signal 412 of the remote power connection modeindicating the remote power disconnect state, so that the remote unit218 is initially powered by the power distribution circuit 244 beforeany testing phases begin. As previously discussed in reference to FIG.5, the controller circuit 404 may be configured to repeatedlycommunicate the remote power connection signal 412 of the remote powerconnection mode indicating the remote power connect state during anormal operation phase, and then communicate the remote power connectionsignal 412 of the remote power connection mode indicating the remotepower disconnect state during a testing phase to continuously detect theexternal load 418 contacting the power conductors 246+, 246−.

It bears repeating that the power distribution circuit 244 may beprovided in any number of different types of communications systems suchas a DAS, RAN, or the like.

FIG. 7 is a graph 700 illustrating exemplary safe and unsafe regions ofbody current for a given current impulse time. The graph 700 plots abody current in mA on the X-axis, and a time impulse exposure durationin ms on the Y-axis. The curve D₁ illustrates a dividing line between asafe region 702 and a danger region 704 for human contact to a current.The shorter the time impulse duration of the current, the safer a humancan withstand a larger body current. For example, according to IEC60947-1, a current of 200 mA that flows through a human body for lessthan 10 ms is regarded to be safe and thus plotted in the safe region702. Therefore, in one example, the power distribution circuit 244 inFIG. 4 is designed in such a way that the close period of thedistribution switch circuit 408 plus the detection time 506 of thecurrent measurement circuit 402 (see FIG. 5) will be lower than 10 ms,assuming that the time between current detection and the disconnectionof the power source 400 from the power conductors 246+, 246− by thedistribution switch circuit 408 is negligible. This is because thecurrent measurement circuit 402 measured the current from the connectedpower source 400 to detect the external load 418, as opposed todetecting the external load 418 through indirect methods, such asthrough the discharge of stored energy in capacitor C₁ that is chargedwhen a power source is connected and discharged during a testing phasewhen the power source is disconnected. In the power distribution circuit244 in FIG. 4, the power source 400 is not decoupled from the powerconductors 246+, 246− during the testing phase when the currentmeasurement circuit 402 is measuring current I₂. As another example, thepower distribution circuit 244 may be configured to detect a body incontact with the power conductors 246+, 246− and cause the distributionswitch circuit 408 to be opened in response within approximately 10 msor less at a 200 mA body current or less as shown in area 706 in graph700. The power distribution circuit 244 may be also configured to detecta body in contact with the power conductors 246+, 246− withinapproximately 20 ms or less at a 100 mA body current or less as shown inarea 708 in graph 700.

FIG. 8 is a schematic diagram illustrating the power distribution system250 in the exemplary form of the DCS 200 (or other communicationssystem) with the power distribution circuit 244 configured to distributepower to a plurality of remote units 218(1)-218(X). Common componentsbetween the DCS 200 and the power distribution system 250 in FIG. 4 andFIG. 8 are shown with common element numbers and will not bere-described. As shown in FIG. 8, a plurality of remote units218(1)-218(X) is provided. Each remote unit 218(1)-218(X) includes aremote power input 409(1)-409(X) coupled to the power conductors246+(1), 246−(1)-246+(X), 246−(X), respectively, which are configured tobe coupled to the power source 400 as previously described in FIG. 4.The power distribution circuit 244 includes a plurality of power outputs8000(1)-8000(X) each configured to provide power to a respectivedistribution switch circuit 408(1)-408(X) and current measurementcircuit 402(1)-402(X), which are assigned to different remote units218(1)-218(X). The current measurement circuits 402(1)-402(X) are eachcoupled to a respective distribution power output 403(1)-403(X) coupledto respective power conductors 246+(1), 246−(1)-246+(X), 246−(X). Thus,the power distribution from the power distribution circuit 244 to theremote units 218(1)-218(X) is in a point-to-multipoint configuration inthis example. The power conductors 246+(1), 246−(1)-246+(X), 246−(X) arealso coupled to remote power inputs 409(1)-409(X). The remote units218(1)-218(X) may also have remote power outputs 802(1)-802(X) that areconfigured to carry power from the respective power conductors 246+(1),246−(1)-246+(X), 246−(X) received on the remote power inputs409(1)-409(X) to an extended remote unit, such as extended remote unit218E.

Also, as shown in the DCS 200 in FIG. 8, the management communicationslinks 410(1)-410(X) to each of the remote units 218(1)-218(X) areprovided by the respective power conductors 246+(1), 246−(1)-246+(X),246−(X). In this example, a plurality of controller circuits404(1)-404(2X) is provided and dedicated to each distribution poweroutput 403(1)-403(X) to control power distribution for each pair ofpower conductors 246+(1), 246−(1)-246+(X), 246−(X) through thedistribution power outputs 403(1)-403(X) to the remote units218(1)-218(X). It should be appreciated that there are 2X controllercircuits 404 because each remote unit has a controller circuit 404 forthe positive power conductor 246+ and a second controller circuit 404for the negative power conductor 246−. As will be discussed in moredetail below, also in this example, a central management circuit 804 isprovided that is configured to send multiplexed communications to eachof the remote units 218(1)-218(X) to send the remote power connectionsignal 412 indicating a remote power disconnect state over a respectivemanagement communications link 410(1)-410(X) to decouple the respectiveremote unit 218(1)-218(X) from the respective power conductor246+(1)-246+(X), thereby disconnecting the load of the remote unit218(1)-218(X) from the power distribution circuit 244 similar topreviously described with regard to FIG. 4. Any measured current I₂ bythe respective current measurement circuit 402(1)-402(X) is communicatedto the respective controller circuit 404(1)-404(X), which is in turncommunicated to the central management circuit 804. In response todetection of the external load 418 as a function of the measured currentI₂ exceeding a predefined threshold current level, the centralmanagement circuit 804 is configured to communicate the distributionpower connection control signal 406(1)-406(X) indicating a distributionpower disconnect state to the respective distribution switch circuit408(1)-408(X) to disconnect the power source 400 from the respectivepower conductors 246+(1), 246−(1)-246+(X), 246−(X) for safety reasons.Also, as shown in FIG. 8, an extended remote unit 218E may be coupled tothe remote unit 218(1) and also configured to receive power from thepower distribution circuit 244 via the remote unit 218(1).

FIG. 9 is a schematic diagram illustrating an exemplary powerdistribution circuit 244 that can be employed as the DCS 200 (or othercommunications system) in FIG. 8. As shown in FIG. 9, a separatepositive side controller circuit 404P and a negative side controllercircuit 404N are provided. This may provide a lower cost solution thanproviding a single controller circuit 404 like in FIG. 4 to controlpower distribution to both the power conductors 246+, 246−. The positiveside controller circuit 404P controls the distribution of power from thepower source 400 provided to the positive distribution power input422I(P) to the power conductor 246+. The negative side controllercircuit 404N controls power from the power source 400 provided to thenegative distribution power input 422I(N) to the power conductor 246−.The previous discussion regarding the features and options of thecontroller circuit 404 above are applicable to the positive sidecontroller circuit 404P and the negative side controller circuit 404N.

With continuing reference to FIG. 9, the negative side controllercircuit 404N is configured to receive first and second currentmeasurements 428N(A), 428N(B) from first and second current measurementcircuits 402N(A), 402N(B). The negative side controller circuit 404N isconfigured to communicate distribution power connection control signals406N(A), 406N(B) to first and second distribution switch circuits408N(A), 408N(B) to control the coupling and decoupling of the powersource 400 to the power conductor 246− as previously described. Thereason for providing the first and second current measurement circuits402N(A), 402N(B) and the first and second distribution switch circuits408N(A), 408N(B) is for redundancy in the event that one of the firstand second current measurement circuits 402N(A), 402N(B) and/or one ofthe first and second distribution switch circuits 408N(A), 408N(B) fail.

Similarly, the positive side controller circuit 404P is configured toreceive first and second current measurements 428P(A), 428P(B) fromfirst and second current measurement circuits 402P(A), 402P(B). Thepositive side controller circuit 404P is also configured to communicatedistribution power connection control signals 406P(A), 406P(B) to firstand second distribution switch circuits 408P(A), 408P(B) to control thecoupling and decoupling of the power source 400 to the power conductor246+ as previously described. The reason for providing the first andsecond current measurement circuits 402P(A), 402P(B) and the first andsecond distribution switch circuits 408P(A), 408P(B) is for redundancyin the event that one of the first and second current measurementcircuits 402P(A), 402P(B) and/or one of the first and seconddistribution switch circuits 408P(A), 408P(B) fail. The powerdistribution system 250 may service multiple remote units 218(1)-218(X)as illustrated in the DCS 200 in FIG. 8. A multiplexer circuit 900,which may also be a combiner circuit, may also be provided as shown inFIG. 9 to multiplex or combine providing remote power connection signals412 over the power conductors 246+, 246−, as previously described.

With continuing reference to FIG. 9, isolation control lines 902A, 902Bare provided between the positive side controller circuit 404P and thenegative side controller circuit 404N. The isolation control line 902Ais used to communicate an immediate alarm signal 904A to both thepositive side controller circuit 404P and the negative side controllercircuit 404N when there is a need to transfer an immediate alarm signal904A to disconnect both the power conductors 246+, 246− due to faultdetection, such as an unwanted overload alarm. Another isolation controlline 902B is provided between the positive side controller circuit 404Pand the negative side controller circuit 404N. The isolation controlline 902B is used as a management link to carry a management signal 904Bfrom the central unit 206 to support management functionalities likesetting new current threshold detection levels for example. Examples ofcurrent detection thresholds can include leakage or unwanted loaddetection and maximum load/overcurrent detection. Another example ofmanagement functionality is to command the power conductors 246+, 246−to be disconnected to prevent a specific load or user from receivingpower.

FIG. 10 is a schematic diagram illustrating additional exemplary detailof additional safety measures that can be provided for the powerdistribution circuit 244 of the power distribution system 250 in FIG. 8.In this example, the controller circuit 404 is configured toperiodically generate a watchdog signal 1000. For example, thecontroller circuit 404 may generate a watchdog signal 1000 every 1 ms. Awatchdog controller 1002 is provided that is configured to receive thewatchdog signal 1000 and provide a watchdog output signal 1004 inresponse. The watchdog output signal 1004 is provided to a logic circuit1006 that is configured to control the distribution power connectioncontrol signal 406. The logic circuit 1006 is designed so that if thewatchdog controller 1002 does not receive the watchdog signal 1000within a specified period of time, this means that the controllercircuit 404 may have failed or otherwise may not be operating properly.In response, the watchdog output signal 1004 will be generated to causethe logic circuit 1006 to provide the distribution power connectioncontrol signal 406 in a distribution power disconnect state to cause thedistribution switch circuit 408 to open and decouple the power source400 from the power distribution circuit 244.

With continuing reference to FIG. 10, if a fault is detected (e.g., anunwanted overload) such that the power should be decoupled form thepower conductors 246+, 246−, the distribution power connection controlsignal 406 indicating the distribution power connection mode indicatinga power disconnection state is also provided to a status LED 1008. Anopto-coupler circuit 1010 is provided that is configured to detect thepower disconnection state from the status LED 1008 and generate theisolation control signal 904 to the positive side controller circuit404P and the negative side controller circuit 404N. This causesdisconnection of power to both the power conductor 246+, 246− due tothis fault detection.

FIG. 11 is a schematic diagram illustrating another exemplary,alternative power distribution circuit 244(1) that is provided in powerdistribution system 250(1) in the exemplary form of a DCS 200(1) similarto the DCS 200 in FIGS. 2A-2C. The power distribution circuit 244(1)includes the power source 400 that is configured to supply power (i.e.,current I₁) to be distributed over the power conductors 246+, 246− to aload 401 of the remote unit 218 to provide power to the remote unit 218for operation of its power consuming components like the powerdistribution circuit 244 in FIG. 4. Common components between the DCS200 in FIG. 4 and the DCS 200(1) in FIG. 11 are shown with commonelement numbers therein, and thus will not be re-described. Componentsshown in the DCS 200(1) in FIG. 11 shown with a label of ‘(N)’ operatelike their counterpart element numbers without the label of ‘(N)’ in theDCS 200 in FIG. 4.

In the DCS 200(1) in FIG. 11, the power source 400 is configured toprovide a differential voltage, in the form of a positive voltage onpower conductor 246+ and a negative voltage on power conductor 246−,with a ground conductor 246G. In this example, this allows an externalload 418(1) connected between power conductors 246+, 246−, an externalload 418(2) connected between power conductors 246+, 246G, and anexternal load 418(3) connected between power conductors 246−, 246G to bedetected by the power distribution circuit 244(1). To detect an externalload 418(3) connected between power conductors 246−, 246G, anothersecond current measurement circuit 402(N) is provided and coupled to thepower conductor 246−. When non-zero current 13 is measured by currentmeasurement circuit 402(N), when remote switch circuit 416 is open, thecontroller circuit 404 uses this as an indication that an external load418(3) is connected between power conductors 426− and 426G and directsthe distribution switch circuit 408(N) to be opened.

The controller circuit 404 may also be configured to compare thecurrents I₂, I₃ measured by current measurement circuits 402, 402(N). Ifthe currents I₂, I₃ are not substantially identical, the controllercircuit 404 may conclude that current flows through an external loadcontacting between either power conductors 246+, 246− to the groundpower conductor 426G. In this instance, the controller circuit 404 maycause distribution switch circuits 408 and 408(N) to both be opened todecouple the power source 400 from power conductors 246+, 246−.

Also as shown in FIG. 11, a distribution multiplexer circuit 1100 isprovided in the power distribution system 250(1). A remote multiplexercircuit 1102 is provided in the remote unit 218. For example, similar topreviously discussed in FIG. 8, the distribution multiplexer circuit1100 may allow a single controller circuit 404 (or central managementcircuit therein as provided in FIG. 8), to communicate the distributionpower connection control signal 406 to a plurality of remote units 218one at a time. The distribution multiplexer circuit 1100 multiplexes theremote units 218, such that the distribution power connection controlsignal 406 is sent to different ones of the remote units 218 one at atime. The multiplexing may be based on frequency-domain multiplexing(FDM) or time-domain multiplexing (TDM) as non-limiting examples. Theremote multiplexer circuit 1102 can demultiplex the distribution powerconnection control signal 406 for instruction.

It may also be desired for example, to include a diode bridge circuit1104 (e.g., a full bridge diode circuit) coupled to the remote powerinput 409 in the remote unit 218 (e.g., can be part of the remotemultiplexer circuit 1102) in case the power distribution circuit 244(1)identifies a fault or unwanted load, and the controller circuit 404disconnects distribution switch circuit 408. The diode bridge circuit1104 can block any potential stored energy from discharging towards thepower conductors 246+, 246−. Adding a diode bridge circuit 1104 can alsomake the remote power input 409 of the remote unit 218 indifferent(i.e., insensitive) to the polarity of the power conductors 246+, 246−such that the remote unit 218 can function even if there is a polarityreversal in the power conductors 246+, 246−. However a drawback may bethat for high current transfer, there is a relatively high power loss inthe diode bridge circuit 1104 (e.g., 5 A on 2 V requires 10 W of heatdissipation).

Note that any of the referenced inputs herein can be provided as inputports or circuits, and any of the referenced outputs herein can beprovided as output ports or circuits.

FIG. 12 is a schematic diagram representation of additional detailillustrating a computer system 1200 that could be employed in anycomponent in the DCS 200, including, but not limited to, the controllercircuits 404 in the power distribution systems 250, 250(1) for couplinga remote unit 218 to the power source 400 during a normal operationphase and instructing the remote unit 218 to decouple from the powersource 400 during testing phases to then measure current from the powersource 400 during a testing phase, including, but not limited to, theDCS 200 in FIGS. 4, 8 and 11 and the controller circuits 404,404(1)-404(X), 404P, 404N in FIGS. 4 and 8-11. In this regard, thecomputer system 1200 is adapted to execute instructions from anexemplary computer-readable medium to perform these and/or any of thefunctions or processing described herein.

In this regard, the computer system 1200 in FIG. 12 may include a set ofinstructions that may be executed to program and configure programmabledigital signal processing circuits in a DCS for supporting scaling ofsupported communications services. The computer system 1200 may beconnected (e.g., networked) to other machines in a LAN, an intranet, anextranet, or the Internet. While only a single device is illustrated,the term “device” shall also be taken to include any collection ofdevices that individually or jointly execute a set (or multiple sets) ofinstructions to perform any one or more of the methodologies discussedherein. The computer system 1200 may be a circuit or circuits includedin an electronic board card, such as, a printed circuit board (PCB), aserver, a personal computer, a desktop computer, a laptop computer, apersonal digital assistant (PDA), a computing pad, a mobile device, orany other device, and may represent, for example, a server or a user'scomputer.

The exemplary computer system 1200 in this embodiment includes aprocessing device or processor 1202, a main memory 1204 (e.g., read-onlymemory (ROM), flash memory, dynamic random access memory (DRAM), such assynchronous DRAM (SDRAM), etc.), and a static memory 1206 (e.g., flashmemory, static random access memory (SRAM), etc.), which may communicatewith each other via a data bus 1208. Alternatively, the processor 1202may be connected to the main memory 1204 and/or static memory 1206directly or via some other connectivity means. The processor 1202 may bea controller, and the main memory 1204 or static memory 1206 may be anytype of memory.

The processor 1202 represents one or more general-purpose processingdevices, such as a microprocessor, central processing unit, or the like.More particularly, the processor 1202 may be a complex instruction setcomputing (CISC) microprocessor, a reduced instruction set computing(RISC) microprocessor, a very long instruction word (VLIW)microprocessor, a processor implementing other instruction sets, orother processors implementing a combination of instruction sets. Theprocessor 1202 is configured to execute processing logic in instructionsfor performing the operations and steps discussed herein.

The computer system 1200 may further include a network interface device1210. The computer system 1200 also may or may not include an input1212, configured to receive input and selections to be communicated tothe computer system 1200 when executing instructions. The computersystem 1200 also may or may not include an output 1214, including, butnot limited to, a display, a video display unit (e.g., a liquid crystaldisplay (LCD) or a cathode ray tube (CRT)), an alphanumeric input device(e.g., a keyboard), and/or a cursor control device (e.g., a mouse).

The computer system 1200 may or may not include a data storage devicethat includes instructions 1216 stored in a computer-readable medium1218. The instructions 1216 may also reside, completely or at leastpartially, within the main memory 1204 and/or within the processor 1202during execution thereof by the computer system 1200, the main memory1204, and the processor 1202 also constituting computer-readable medium.The instructions 1216 may further be transmitted or received over anetwork 1220 via the network interface device 1210.

While the computer-readable medium 1218 is shown in an exemplaryembodiment to be a single medium, the term “computer-readable medium”should be taken to include a single medium or multiple media (e.g., acentralized or distributed database, and/or associated caches andservers) that store the one or more sets of instructions. The term“computer-readable medium” shall also be taken to include any mediumthat is capable of storing, encoding, or carrying a set of instructionsfor execution by the processing device and that cause the processingdevice to perform any one or more of the methodologies of theembodiments disclosed herein. The term “computer-readable medium” shallaccordingly be taken to include, but not be limited to, solid-statememories, optical medium, and magnetic medium.

The embodiments disclosed herein include various steps. The steps of theembodiments disclosed herein may be formed by hardware components or maybe embodied in machine-executable instructions, which may be used tocause a general-purpose or special-purpose processor programmed with theinstructions to perform the steps. Alternatively, the steps may beperformed by a combination of hardware and software.

The embodiments disclosed herein may be provided as a computer programproduct, or software, that may include a machine-readable medium (orcomputer-readable medium) having stored thereon instructions, which maybe used to program a computer system (or other electronic devices) toperform a process according to the embodiments disclosed herein. Amachine-readable medium includes any mechanism for storing ortransmitting information in a form readable by a machine (e.g., acomputer). For example, a machine-readable medium includes: amachine-readable storage medium (e.g., ROM, random access memory(“RAM”), a magnetic disk storage medium, an optical storage medium,flash memory devices, etc.); and the like.

Unless specifically stated otherwise and as apparent from the previousdiscussion, it is appreciated that throughout the description,discussions utilizing terms such as “processing,” “computing,”“determining,” “displaying,” or the like, refer to the action andprocesses of a computer system, or similar electronic computing device,that manipulates and transforms data and memories represented asphysical (electronic) quantities within the computer system's registersinto other data similarly represented as physical quantities within thecomputer system memories or registers or other such information storage,transmission, or display devices.

The algorithms and displays presented herein are not inherently relatedto any particular computer or other apparatus. Various systems may beused with programs in accordance with the teachings herein, or it mayprove convenient to construct more specialized apparatuses to performthe required method steps. The required structure for a variety of thesesystems will appear from the description above. In addition, theembodiments described herein are not described with reference to anyparticular programming language. It will be appreciated that a varietyof programming languages may be used to implement the teachings of theembodiments as described herein.

Those of skill in the art will further appreciate that the variousillustrative logical blocks, modules, circuits, and algorithms describedin connection with the embodiments disclosed herein may be implementedas electronic hardware, instructions stored in memory or in anothercomputer-readable medium and executed by a processor or other processingdevice, or combinations of both. The components of the distributedantenna systems described herein may be employed in any circuit,hardware component, integrated circuit (IC), or IC chip, as examples.Memory disclosed herein may be any type and size of memory and may beconfigured to store any type of information desired. To clearlyillustrate this interchangeability, various illustrative components,blocks, modules, circuits, and steps have been described above generallyin terms of their functionality. How such functionality is implementeddepends on the particular application, design choices, and/or designconstraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentembodiments.

The various illustrative logical blocks, modules, and circuits describedin connection with the embodiments disclosed herein may be implementedor performed with a processor, a Digital Signal Processor (DSP), anApplication Specific Integrated Circuit (ASIC), a Field ProgrammableGate Array (FPGA), or other programmable logic device, a discrete gateor transistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. Furthermore,a controller may be a processor. A processor may be a microprocessor,but in the alternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices (e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration).

The embodiments disclosed herein may be embodied in hardware and ininstructions that are stored in hardware, and may reside, for example,in RAM, flash memory, ROM, Electrically Programmable ROM (EPROM),Electrically Erasable Programmable ROM (EEPROM), registers, a hard disk,a removable disk, a CD-ROM, or any other form of computer-readablemedium known in the art. An exemplary storage medium is coupled to theprocessor such that the processor can read information from, and writeinformation to, the storage medium. In the alternative, the storagemedium may be integral to the processor. The processor and the storagemedium may reside in an ASIC. The ASIC may reside in a remote station.In the alternative, the processor and the storage medium may reside asdiscrete components in a remote station, base station, or server.

It is also noted that the operational steps described in any of theexemplary embodiments herein are described to provide examples anddiscussion. The operations described may be performed in numerousdifferent sequences other than the illustrated sequences. Furthermore,operations described in a single operational step may actually beperformed in a number of different steps. Additionally, one or moreoperational steps discussed in the exemplary embodiments may becombined. Those of skill in the art will also understand thatinformation and signals may be represented using any of a variety oftechnologies and techniques. For example, data, instructions, commands,information, signals, bits, symbols, and chips, that may be referencesthroughout the above description, may be represented by voltages,currents, electromagnetic waves, magnetic fields, or particles, opticalfields or particles, or any combination thereof

Unless otherwise expressly stated, it is in no way intended that anymethod set forth herein be construed as requiring that its steps beperformed in a specific order. Accordingly, where a method claim doesnot actually recite an order to be followed by its steps, or it is nototherwise specifically stated in the claims or descriptions that thesteps are to be limited to a specific order, it is in no way intendedthat any particular order be inferred.

It will be apparent to those skilled in the art that variousmodifications and variations can be made without departing from thespirit or scope of the invention. Since modifications, combinations,sub-combinations and variations of the disclosed embodimentsincorporating the spirit and substance of the invention may occur topersons skilled in the art, the invention should be construed to includeeverything within the scope of the appended claims and theirequivalents.

What is claimed is:
 1. A power distribution system comprising: one ormore power distribution circuits each comprising: a distribution powerinput configured to receive current distributed by a power source; adistribution power output configured to distribute the received currentover a power conductor coupled to an assigned radio communicationscircuit of a remote unit among a plurality of remote units; adistribution switch circuit coupled between the distribution power inputand the distribution power output, the distribution switch circuitcomprising a distribution switch control input configured to receive adistribution power connection control signal indicating a distributionpower connection mode; the distribution switch circuit configured to beclosed to couple the distribution power input to the distribution poweroutput in response to the distribution power connection mode indicatinga distribution power connect state; and the distribution switch circuitfurther configured to be opened to decouple the distribution power inputfrom the distribution power output in response to the distribution powerconnection mode indicating a distribution power disconnect state; and acurrent measurement circuit coupled to the distribution power output andcomprising a current measurement output; the current measurement circuitconfigured to measure a current at the distribution power output andgenerate a current measurement on the current measurement output basedon the measured current at the distribution power output; and acontroller circuit comprising: one or more current measurement inputscommunicatively coupled to the one or more current measurement outputsof the one or more current measurement circuits of the one or more powerdistribution circuits; and the controller circuit configured to, for apower distribution circuit among the one or more power distributioncircuits: generate the distribution power connection control signalindicating the distribution power connection mode to the distributionswitch control input of the power distribution circuit indicating thedistribution power connect state; determine if the measured current on acurrent measurement input among the one or more current measurementinputs of the power distribution circuit exceeds a predefined thresholdcurrent level when the distribution switch circuit is closed to couplethe distribution power input to the distribution power output; and inresponse to the measured current of the power distribution circuitexceeding the predefined threshold current level, communicate thedistribution power connection control signal indicating the distributionpower connection mode to the distribution switch control input of thepower distribution circuit indicating the distribution power disconnectstate.
 2. The power distribution system of claim 1, wherein: each powerdistribution circuit of the one or more power distribution circuitsfurther comprises: a second current measurement circuit coupled to thecurrent measurement circuit, and comprising a second current measurementoutput; the second current measurement circuit configured to measure thecurrent at the distribution power output and generate a second currentmeasurement on the second current measurement output based on themeasured current at the distribution power output; and the controllercircuit further comprises: one or more second current measurement inputscommunicatively coupled to the one or more second current measurementoutputs of the one or more second current measurement circuits of theone or more power distribution circuits; and the controller circuitfurther configured to, for a power distribution circuit among the one ormore power distribution circuits: determine if the measured current on asecond current measurement input among the one or more second currentmeasurement inputs of the power distribution circuit exceeds thepredefined threshold current level; and in response to the measuredcurrent of the power distribution circuit exceeding the predefinedthreshold current level, communicate the distribution power connectioncontrol signal comprising the distribution power connection mode to thedistribution switch control input of the power distribution circuitindicating the distribution power disconnect state.
 3. The powerdistribution system of claim 1, wherein: each power distribution circuitof the one or more power distribution circuits further comprises: asecond current measurement circuit comprising a second currentmeasurement output; the second current measurement circuit configured tomeasure a second current at a second distribution power output andgenerate a second current measurement on the second current measurementoutput based on the second measured current received on the seconddistribution power output; and the controller circuit further comprises:one or more second current measurement inputs communicatively coupled tothe one or more second current measurement outputs of the one or moresecond current measurement circuits of the one or more powerdistribution circuits; and the controller circuit further configured to,for a power distribution circuit among the one or more powerdistribution circuits: determine a differential measured current betweenthe measured current on the current measurement input and the secondmeasured current on a second current measurement input; determine if thedifferential measured current exceeds the predefined threshold currentlevel; and in response to the differential measured current of the powerdistribution circuit exceeding the predefined threshold current level,communicate the distribution power connection control signal comprisingthe distribution power connection mode to the distribution switchcontrol input of the power distribution circuit indicating thedistribution power disconnect state.
 4. The power distribution system ofclaim 1, wherein the controller circuit is further configured toperiodically generate a watchdog signal; and further comprising awatchdog controller configured to: receive the watchdog signal; inresponse to not receiving the watchdog signal within a predefined timeperiod, cause the distribution power connection control signal toindicate the distribution power disconnect state.
 5. The powerdistribution system of claim 1, wherein the predefined threshold currentlevel is less than 200 milliAmps (mA).
 6. The power distribution systemof claim 1, wherein the predefined threshold current level is less than100 milliAmps (mA).
 7. The power distribution system of claim 1, furthercomprising a housing containing the controller circuit, the currentmeasurement circuit, and the power source.
 8. The power distributionsystem of claim 1, wherein the controller circuit is further configuredto: lower a voltage level on the distribution power output from a firstvoltage level to a second voltage level distributing the receivedcurrent over the power conductor coupled to the remote unit; raise thevoltage level on the distribution power output from the second voltagelevel to the first voltage level distributing the received current overthe power conductor coupled to the remote unit; and determine if themeasured current on the current measurement input among the one or morecurrent measurement inputs of the power distribution circuit exceeds thepredefined threshold current level when the distribution switch circuitis closed to couple the distribution power input to the distributionpower output in response to raising the voltage level on the powerdistribution output.
 9. A method of disconnecting current from a powersource, comprising: decoupling current from a power conductor to a radiocommunications circuit of a remote unit; measuring a current receivedfrom a power source coupled to the power conductor; determining if themeasured current exceeds a predefined threshold current level; and inresponse to the measured current exceeding the predefined thresholdcurrent level, communicating a distribution power connection controlsignal comprising a distribution power connection mode indicating adistribution power disconnect state to cause the power conductor to bedecoupled from the power source.
 10. The method of claim 9, furthercomprising, in response to the measured current of a power distributioncircuit not exceeding the predefined threshold current level,communicating the distribution power connection control signalindicating a distribution power connect state to cause the powerdistribution circuit to couple to the power source.
 11. The method ofclaim 9, further comprising multiplexing the distribution powerconnection control signal and a remote power connection signal to theremote unit.
 12. The method of claim 9, further comprising combining thedistribution power connection control signal and a remote powerconnection signal to the remote unit.
 13. The method of claim 9, furthercomprising: periodically generating a watchdog signal; and in responseto not receiving the watchdog signal within a predefined time period,causing the distribution power connection control signal to indicate thedistribution power disconnect state.
 14. The method of claim 9, furthercomprising: lowering a voltage level on the power conductor from a firstvoltage level to a second voltage level; and raising the voltage levelon the power conductor from the second voltage level to the firstvoltage level; wherein: measuring the current comprises measuring thecurrent received from the power source coupled to the power conductorafter raising the voltage level on the power conductor.
 15. Adistributed communications system (DCS), comprising: a central unitconfigured to: distribute received one or more downlink communicationssignals over one or more downlink communications links to one or moreremote units; distribute received one or more uplink communicationssignals from the one or more remote units from one or more uplinkcommunications links to one or more source communications outputs; aplurality of remote units, each remote unit among the plurality ofremote units comprising: at least one radio communications circuit; aremote power input coupled to a power conductor carrying current from apower distribution circuit; a remote switch control circuit configuredto generate a remote power connection signal indicating a remote powerconnection mode; and a remote switch circuit comprising a remote switchinput configured to receive the remote power connection signal; theremote switch circuit configured to be closed to couple to the remotepower input in response to the remote power connection mode indicating aremote power connect state; and the remote switch circuit furtherconfigured to be opened to decouple from the remote power input inresponse to the remote power connection mode indicating a remote powerdisconnect state; the remote unit configured to: distribute through theat least one radio communications circuit, the received one or moredownlink communications signals received from the one or more downlinkcommunications links, to one or more client devices; and distribute thereceived one or more uplink communications signals from the one or moreclient devices to the one or more uplink communications links; and apower distribution system comprising: one or more power distributioncircuits each comprising: a distribution power input configured toreceive current distributed by a power source; a distribution poweroutput configured to distribute the received current over the powerconductor coupled to an assigned remote unit among the plurality ofremote units; a distribution switch circuit coupled between thedistribution power input and the distribution power output, thedistribution switch circuit comprising a distribution switch controlinput configured to receive a distribution power connection controlsignal indicating a distribution power connection mode; the distributionswitch circuit configured to be closed to couple the distribution powerinput to the distribution power output in response to the distributionpower connection mode indicating a distribution power connect state; andthe distribution switch circuit further configured to be opened todecouple the distribution power input from the distribution power outputin response to the distribution power connection mode indicating adistribution power disconnect state; and a current measurement circuitcoupled to the distribution power output and comprising a currentmeasurement output; the current measurement circuit configured tomeasure a current at the distribution power output and generate acurrent measurement on the current measurement output based on themeasured current at the distribution power output; and a controllercircuit comprising: one or more current measurement inputscommunicatively coupled to the one or more current measurement outputsof the one or more current measurement circuits of the one or more powerdistribution circuits; the controller circuit configured to, for a powerdistribution circuit among the one or more power distribution circuits:generate the distribution power connection control signal indicating thedistribution power connection mode to the distribution switch controlinput of the power distribution circuit indicating the distributionpower connect state; determine if the measured current on a currentmeasurement input among the one or more current measurement inputs ofthe power distribution circuit exceeds a predefined threshold currentlevel; and in response to the measured current of the power distributioncircuit exceeding the predefined threshold current level, communicatethe distribution power connection control signal comprising thedistribution power connection mode to the distribution switch controlinput of the power distribution circuit indicating the distributionpower disconnect state.
 16. The DCS of claim 15, wherein the controllercircuit is further configured to: lower a voltage level on thedistribution power output from a first voltage level to a second voltagelevel distributing the received current over the power conductor coupledto the assigned remote unit; raise the voltage level on the distributionpower output from the second voltage level to the first voltage leveldistributing the received current over the power conductor coupled tothe assigned remote unit; and determine if the measured current on thecurrent measurement input among the one or more current measurementinputs of the power distribution circuit exceeds the predefinedthreshold current level when the distribution switch circuit is closedto couple the distribution power input to the distribution power outputin response to raising the voltage level on the power distributionoutput.
 17. The DCS of claim 15, further comprising one or more extendedremote units, each extended remote unit among the one or more extendedremote units comprising: an extended remote communications input coupledto an extended downlink communications link coupled to a remote unitamong the plurality of remote units; a remote communications outputcoupled to an extended uplink communications link coupled to the remoteunit; and an extended remote power input coupled to an extended powerconductor carrying current from the remote unit to the extended remoteunit.
 18. The DCS of claim 15, wherein the central unit is configuredto: distribute each of the received one or more downlink communicationssignals over a distribution communications output among a plurality ofdistribution communications outputs to a downlink communications linkamong the one or more downlink communications links; and distribute eachof the received one or more uplink communications signals from an uplinkcommunications link among the one or more uplink communications links ona distribution communications input among a plurality of distributioncommunications inputs, to the one or more source communications outputs.19. The DCS of claim 15 comprising a distributed antenna system (DAS).20. The DCS of claim 15, wherein: the one or more downlinkcommunications links comprise one or more optical downlinkcommunications links; the one or more uplink communications linkscomprise one or more optical uplink communications links; and thecentral unit further comprises: one or more electrical-to-optical (E-O)converters configured to convert received one or more electricaldownlink communications signals into one or more optical downlinkcommunications signals; and one or more optical-to-electrical (O-E)converters configured to convert received one or more optical uplinkcommunications signals into one or more electrical uplink communicationssignals; the central unit further configured to: distribute the one ormore optical downlink communications signals from the one or more E-Oconverters over a plurality of optical distribution communicationsoutputs to the one or more optical downlink communications links; anddistribute the received one or more optical uplink communicationssignals from the one or more optical uplink communications links on aplurality of optical distribution communications inputs to the one ormore O-E converters; wherein each remote unit among the plurality ofremote units further comprises: one or more O-E converters configured toconvert the received one or more optical downlink communications signalsinto one or more electrical downlink communications signals; and one ormore E-O converters configured to convert received one or moreelectrical uplink communications signals into the one or more opticaluplink communications signals; each remote unit among the plurality ofremote units configured to: distribute the one or more electricaldownlink communications signals from the one or more O-E converters, tothe one or more client devices; and distribute the one or more opticaluplink communications signals from the one or more E-O converters to theone or more optical downlink communications links. 21-24. (canceled)